A common objection against infant baptism by credo-baptists is that if children are to be baptized, then, for the sake of consistency, they ought to also be admitted to the Lord’s Supper. In other words, the logical conclusion of infant baptism necessarily leads to the absurdity of infant communion; paedocommunion is obviously unbiblical and absurd, therefore paedobaptism must likewise be unbiblical. In like manner, paedocommunion advocates endorse the same logic, but instead of denying both infant baptism and infant communion, they affirm and practice both under the same pretense of consistency (cf. Infant Communion? By Douglas Wilson). Since paedobaptism is true, paedocommunion is likewise true, and it is inconsistent to treat them differently by giving one sacrament to infants but not the other.
But is this charge of inconsistency a valid criticism of confessional Reformed sacramentology?
Baptists and Paedocommunionists both hold to the same naive and superficial assumption: “Since Baptism and the Lord’s Supper are both sacraments, they must also have the same qualifications for partaking worthily.” But this is not a sound conjecture, it is a false analogy. On the contrary, confessional Reformed Theology rightly affirms that the Lord Jesus Christ defines the manner in which each sacrament ought to be partaken of—and he does so in harmonious consistency with the nature, use, and ends that he himself instituted for each sacrament respectively.
So the remaining question is, why do confessional Reformed churches baptize infants, but do not admit them to the Lord’s Table? They do so for the following three reasons:
1) Covenant Status & the Requirements for Partaking of Each Sacrament.
First, due to their covenant status, personal acts of faith (such as a credible profession) are not necessary for infants to be baptized, but yet they are necessary for them to partake of the Lord’s Supper.
A credible profession of faith, as validated by the elders of the church, is required of those outside of the visible church in order for them to join the covenant community. Converts to Christianity must enter the covenant community first, by professing faith in Christ, and then they can be admitted to the sacrament of baptism (Mark 16:15-16; Acts 8:37-38). However, infants of believers are already members of the covenant community, and are federally holy (Gen. 9:9; Gen. 17:10; Acts 2:39; 1 Cor. 7:14; cf. WLC 166). As members of the visible church, covenant infants have a right to the initiatory sacrament of baptism. That is why a profession of faith is not required of covenant infants before receiving baptism. 
Unlike the requirements for adult baptism, the requirements for worthily partaking of the Lord’s Supper are not given to unbelievers, but rather to the covenant community. There is no similar twofold requirement for this sacrament like there is for baptism with regard to unbelieving adults vs covenant children. This sacrament is exclusively for covenant members, not for outsiders of the covenant—which is why the prerequisites for worthy partaking are the same for all those who already are covenant members. These prerequisites are remembering Christ (1 Cor. 11:24-25), self-examination (1 Cor. 11:28; 2 Cor. 13:5), discerning the Lord’s body and blood (1 Cor. 11:27, 29), taking, eating, and drinking the bread and the wine (1 Cor. 11:24-25), not just physically, but spiritually by faith (John 6:35; 1 Cor. 11:26). As William Ames wrote,
“Baptism ought to be administered to all those in the covenant of grace, because it is the first sealing of the covenant now first entered into… But the Supper is to be administered only to those who are visibly capable of nourishment and growth in the church. Therefore, it is to be given not to infants, but only to adults.” (Marrow of Theology I.xl.11, 18, pp. 211 & 212)
Baptism requires covenant membership, which is obtained either by birth or by profession of faith. Covenant children are not an exception to this rule. Communion requires not only covenant membership, but also multiple spiritual exercises which are not required for any party in baptism. Of these spiritual exercises, John Calvin writes, “Nothing of the kind is prescribed by baptism. Wherefore, there is the greatest difference between the two signs [baptism & communion].” He continues with an analogy from the old covenant sacraments:
“This also we observe in similar signs under the old dispensation. Circumcision, which, as is well known, corresponds to our baptism, was intended for infants, but the Passover, for which the Supper is substituted, did not admit all kinds of guests promiscuously, but was duly eaten only by those who were of an age sufficient to ask the meaning of it (Exod. 12:26).” (Institutes of the Christian Religion IV.xvi.30)
Hence it is clear that the prerequisites for baptism are not comparable to those for the Lord’s Supper. The requirement for baptism is that one be a member of the visible church, yet one may become a member of the visible church in two ways. Non-covenanted individuals outside the church must profess faith in Christ to join the church and be baptized, whereas members of the church already have a right to baptism. However, the requirements for the Lord’s Supper, discussed above, cannot be met in multiple ways.
2) The Manner of Participation.
Secondly, the recipient is passive in baptism, but active in communion. One is baptized by being a covenant member, and having water poured on the head, whereas in communion there are several physical and spiritual actions that must take place. The participant does not baptize himself, but in communion, the participant takes, eats, drinks, and remembers.
This passive and active manner of participation corresponds to the Christ-ordained ends of the two sacraments respectively. Baptism represents regeneration (Titus 3:5)—which is an irresistible act of the Holy Ghost upon the passive person (John 3:8) bringing him to spiritual life (Ezekiel 37:1-10; Eph. 2:5) and giving him a new heart (Ezekiel 36:26). Yet, Communion represents active faith (John 6:35; 1 Cor. 11:26)—which is an act of the believer reaching out and taking hold of Christ for himself unto salvation (John 1:12; Acts 15:11; 16:31; Gal 2:20). It is important to remember that justifying faith consists of three components: knowledge of the gospel message (notitia), intellectual assent acknowledging the truth of the gospel message (assensus), and wilful trust in, and a faithful apprehending of, the promises of God in Christ unto oneself (fiducia). This knowledge and assent are intellectual actions, and fiducial trust is an act of the will  — all three of which infants in their stage of development are not yet capable of (Isa. 7:16; Rom. 10:17; 12:1).  Yet, regeneration, being the sole act of the Holy Ghost, infants are capable of receiving (John 3:8). As Robert Baillie (1602-1662) wrote,
“[Infants] are not capable of the whole signification of the Lord’s Supper, for the thing signified therein is not the Lord’s body and blood simply, but his body to be eaten, and his blood to be drunken, by the actual faith of the communicants; of this active application infants are not capable; but in baptism no action is necessarily required of all who are to be baptized; for as the body may be washed without any action of the party who is washed: so the virtue of Christ’s death and life may be applied in remission and regeneration, by the act of God alone to the soul as a mere patient without any action from it.” (Anabaptism, the True Fountain of Independency, pp. 151-152).
Furthermore, this “taking,” “eating,” and “drinking” in the Supper are not only to be understood as physical actions, but as the spiritual actions of the subject. As Augustine said, “Why dost thou prepare thy teeth and belly? Believe, and thou hast eaten.” (Tractate 25). Matthew Henry similarly comments,
“This is here exhibited, or set forth, as the food of souls. And as food, though ever so wholesome or rich, will yield no nourishment without being eaten, here the communicants are to take and eat, or to receive Christ and feed upon him, his grace and benefits, and by faith convert them into nourishment to their souls.” (Com. 1 Cor. 11:24). 
Hence, infants are capable of physically and spiritually participating in baptism (passively), but are not capable of participating actively in the Lord’s Supper. This will become more clear in our next point.
3) Infants benefit from baptism but not from the Supper.
Thirdly, regarding the efficacy of the sacraments, infants benefit from baptism outwardly and are able to inwardly, whereas they can not benefit from the Supper in either way.
Covenant children benefit from baptism outwardly in that they are publicly admitted into the visible church (Acts 2:41; Gal. 3:27; Eph. 5:26) and dedicated to Christ to walk in newness of life (Rom. 6:3-4). In baptism “we are received into the Church of God, and separated from all other people and strange religions [Acts 2:39], that we may wholly belong to him, whose ensign and banner we bear: and which serves as a testimony to us, that he will forever be our gracious God and Father.” (Belgic Confession, art. 34). These things are true of covenant children regardless of their personal active intent at the time of administration. Furthermore, baptized children are covenantally obligated to improve their baptism as they grow through the diligent use of the means of grace, which they now have access to as a baptized member of the visible church. James Ussher explains this well when answering the question, “What is the advantage then or benefit of baptism to a common Christian?” He writes,
“The same as was the benefit of Circumcision to the Jew outward (Rom. 2.28; Rom. 3.1-2), there is a general grace of Baptism which all the baptized partake of as a common favour, and that is their admission into the visible body of the Church, their matriculation and outward incorporating into the number of the worshippers of God by external communion: and so as Circumcision was not only a seal of the righteousness which is by faith, but as an overplus God appointed it to be like a wall of separation between Jew and Gentile; so is Baptism a badge of an outward member of the Church, a distinction from the common rout of Heathen; and God thereby seals a right upon the party baptized to his ordinances, that he may use them as his privileges, and wait for an inward blessing by them; yet this is but the porch, the shell, and outside; all that are outwardly received into the visible Church, are not spiritually engrafted into the mystical body of Christ. Baptism always is attended upon by that general grace, but not always with this special.” (Body of Divinity, p. 375).
Mere outward partakers of baptism benefit from baptism in this regard, although they are obligated to internalize the meaning of their baptized status and grow into a personal and lively faith in Christ in due time. Even so, such cannot be said of the Lord’s Supper.
There is no similar benefit to mere outward partaking of the Lord’s Supper, because it is not a one time public recognition of a change of status, but rather an often practiced spiritual exercise. The outward benefits of baptism discussed above are subsumed into the observance of the Lord’s Supper because one qualification is that partakers be baptized, but many more qualifications are required in addition to this. The repeated spiritual exercise of baptism is improving it, whereas partaking of the Lord’s Supper is itself the repeated spiritual exercise. Traditional Reformed Theology does not expect infants to be capable of engaging in either. 
However, infants without the ability to have active faith cannot benefit from partaking in the Lord’s Supper. Though they may or may not be regenerate, infants are not yet capable of the acts of faith, and hence cannot have this faith nourished and grown in the use of the Lord’s Supper. Nor can they express it and have it verified by the elders—who are the stewards of the mysteries of God (1 Cor. 4:1). They cannot spiritually receive and feed upon Christ, they can only partake outwardly—which renders the sacrament useless to them until they can act in faith (knowledge, willful assent, and fiducial trust in Christ).
Assuming that Paedocommunionists do not intend to imply an ex opere operato mechanism of sacramental efficacy, the only perceived benefit of admitting infants to the Table would be to acknowledge that they are objective (outward) members of the covenant community. However, this benefit is already enjoyed by covenant children in their baptism. Hence, in eagerly desiring to emphasize this benefit, Paedocommunionists inadvertently undermine and diminish the significance of baptism and treat it as though it were insufficient for this Christ-ordained purpose.
Infants of believers also may benefit from baptism in principle, spiritually. As we said, baptism signifies spiritual birth, or regeneration, while communion represents the continual feasting on Christ by faith and the spiritual growth and nourishment that comes with it (John 6:35; 1 Cor. 11:26). In principle, regeneration is possible before or during baptism, but active faith is not possible for the infant in communion. In other words, at the time of administration, covenant infants are capable of the grace signified by baptism (Jer. 1:5; Luke 1:15; John 3:8), but not the grace signified by communion. So, even though we confess that “the efficacy of baptism is not tied to that moment of time wherein it is administered” (WCF 28:6), the signification of baptism, in principle, remains prior to, and during, the time of administration. This is not the case for the Lord’s Supper because the signification of it requires active faith, and a verifiable profession of such faith by the elders (1 Cor. 4:1; 5:11). As Stephen Marshall (1594-1655) wrote:
“[That] infants are capable of the grace of Baptism we are sure, [but we are] not sure that they are capable of the grace signed and sealed in the Sacrament of the Lord’s Supper. For though both of them are seals of the New Covenant, yet it is with some difference: Baptism properly seals the entrance into it, the Lord’s Supper properly [seals] the growth, nourishment, and augmentation of it. Baptism for our birth, the Lord’s Supper for our food. Now, infants may be born again while they are infants, have their original sin pardoned, be united to Christ, have his image stamped upon them, but concerning the exercise of these graces and augmentation of them in infants, while they are infants, the Scripture is altogether silent.” (A Sermon of the Baptizing of Infants, pp. 51-52).
It makes sense that Paedocommunion advocates would misunderstand this, for two reasons: 1) because, in general, they denigrate Experimental Religion, and, 2) they typically hold to a perspective of covenant membership which, similar to Baptist doctrine, univocally collapses the visible and invisible church, rather than a confessional view (which distinguishes them rightly). For a critical examination of these things, see Michael J. Ericson’s Critique of the Teachings of Barach, Schlissel, Wilkins, and Wilson. 
This is worth emphasizing. Paedocommunionists’ misguided sacramentology follows directly from their misguided soteriology and ecclesiology. Paedocommunion advocates indiscriminately collapse and gloss over the degrees by which God works faith within covenant children. In contrast, Petrus Van Mastricht summarizes biblical, Reformed soteriology pertinent to this topic:
“God works faith, first, in regeneration, whereby he confers the seed of faith, that by it we may be able to believe at the proper time, once all things needed are supplied. Before this regeneration, as we said, a person is dead to every spiritual good. Second, God works faith in conversion, whereby the seed of faith sends forth shoots, such that we actually believe, take hold of Christ as our one and only Mediator, and having been drawn to him, come (John 6:44), run (Song 1:4), and lean on Christ (Song 8:5). Third, God works faith in sanctification, whereby faith puts our flower and fruit, and is at work through love (Gal. 5:6).” (Theoretical-Practical Theology I.ii.1.21, vol. 2, p. 14; cf. ibid., pp. 7 & 35). 
We must distinguish between the “grace of faith” and the “principle acts of faith” (WCF 14:1-2), also called the seed or habit of faith (semen/habitus fidei) versus the actualizing operation of faith (actus fidei).  This seed of faith is a disposition of the soul after regeneration and the capacity to have faith; it is an irresistible gift of the Holy Ghost in the hearts of the elect. Mastricht defines seminal faith as “the power of believing, which God, without our zeal, confers immediately by virtue of regeneration, by making us alive, taking away our stony heart, etc.”. This seed of faith is contrasted with actual faith, “by which once made alive in regeneration and having obtained the ability to believe, we strive that in actuality we may take hold of God as our highest end and Christ as the one and only Mediator.” (ibid., p. 35; similarly Francis Turretin, Institutes of Elenctic Theology XV.xiv, vol. 2, pp. 583-587). The Westminster Confession likewise states, “By this faith a Christian believeth to be true whatsoever is revealed in the Word…But the principal acts of saving faith are accepting, receiving, and resting upon Christ alone for justification, sanctification, and eternal life…” (14:2).
While regeneration and actual faith in response to hearing the gospel are ordinarily simultaneous in adults, it is not so in elect infants regenerated in infancy,  who Mastricht says, “believe at the proper time, once all things needed are supplied,” such as the gospel message in the outward call.  Turretin further explains, “Although age contributes nothing to faith as the efficient cause per se, still it is required for it as a receptive subject (because a thing is received after the manner of the recipient)” (IET XV.xiv.6). And this is assumed by Scripture which says that there is a time before children (even Christ according to his human nature) are able to “know to refuse the evil, and choose the good” (Isa. 7:16), that “faith cometh by hearing” and of course understanding (Rom. 10:17), and that the whole of religion is the Christian’s “reasonable service” (Rom. 12:1).
In conclusion, a seed of faith is insufficient for partaking of the Lord’s Supper, rather active faith is needed. The very reason Calvin gives for infants having an interest in baptism is the same reason they do not yet have an interest in the Lord’s Supper. He writes,
“If we attend to the peculiar nature of baptism, it is a kind of entrance, and as it were initiation into the Church, by which we are ranked among the people of God, a sign of our spiritual regeneration, by which we are again born to be children of God; whereas, on the contrary, the Supper is intended for those of riper years, who, having passed the tender period of infancy, are fit to bear solid food. This distinction is very clearly pointed out in Scripture.” (Institutes of the Christian Religion, 4.16.30).
Zacharias Ursinus, more poignantly,
“Infants are not capable of coming to the Lord’s Supper, because they do not possess faith actually, but only potentially and by inclination [i.e. a seed of faith]. But here actual faith is required, which includes a certain knowledge of what God has revealed, and an assured confidence in Christ; it also requires the commencement of a new obedience, and purpose to live godly; and also an examination of ourselves, with a commemoration of the Lord’s death.” (Commentary on the Heidelberg Catechism, p. 425).
We have seen that there are three reasons infant baptism does not logically necessitate infant communion. And moreover, these very principles of infant baptism militate against any such idea of infant communion. First, the requirement for baptism is that one be a member of the visible church, entering either by profession of faith or by federal relationship. However, the requirements for the Lord’s Supper are prescribed by Christ to be commonly applicable to all potential communicants in the covenant community. This is because the sacraments were ordained for their own particular uses. Secondly, the passive and active manner of participation for each, corresponds to the Christ-ordained ends of the two sacraments respectively. Conflating these ends, or their particular uses, denigrates Christ’s design as well as his authority and prerogative. Lastly, infants benefit from baptism 1) outwardly, by their public admittance into the visible church and dedication to Christ to walk in newness of life, and 2) inwardly, by signification, promise, and sealing of spiritual birth. Yet at the same time they can not benefit from the Supper in these ways until they mature in their faith and can actively participate. Bringing the two sacraments together, Cornelius Venema concludes:
“There is a direct pathway from the baptismal font to the Lord’s Supper, and it is the duty of the Christian church to exert itself in instructing the children of believing parents in the Christian faith so that they might follow this path. Such children need to be reminded constantly of the great privileges and corresponding obligations of their membership in the covenant community and of their baptism. When these children are properly instructed in the faith, the church may expectantly anticipate that they will profess that faith as their own and be admitted to the Table of the Lord, where their faith will enjoy a most wondrous feast of thanksgiving and communion with the crucified and risen Lord.” (Children at the Lord’s Table?, pp. 148-149).
 “It might seem that there was a difference between the baptism of adults and that of children. The adults to be baptized on the ground of their faith, infants, on the ground of the covenant of God. No, the Reformer [i.e. Calvin] declares, the only rule according to which, and the legal ground on which, the Church may administer baptism, is the covenant. This is true in the case of adults as well as in the case of children. That the former must first make a confession of faith and conversion, is due to the fact that they are outside of the covenant. In order to be admitted into the communion of the covenant, they must first learn the requirements of the covenant, and then faith and conversion open the way to the covenant.” (Louis Berkhof, Systematic Theology, p. 640).
 Richard Muller, Dictionary of Latin & Greek Theological Terms, 2nd Ed. (2017), fides, p. 121. Justifying faith “not only assenteth to the truth of the promise of the gospel, but receiveth and resteth upon Christ and his righteousness therein held forth” (Westminster Larger Catechism 72).
 cf. Francis Turretin, Institutes of Elenctic Theology XV.xiv, vol. 2, pp. 583-587.
 The required actions of the communicants to “take” and “eat” (1 Cor. 11:24) is violated both by Rome placing it in communicants’ mouths and by Paedocommunionists doing the same with infants.
 At this point, the Paedocommunionist might then suggest that preparation and reception of the Lord’s Supper need not be as rigorous as traditional Reformed Theology has practiced, and might be as simple as requiring a child to say “I love Jesus.” However, that would be to abandon the core Paedocommunion stance that covenant status is the lone requirement, and to concede that confessional Reformed Theology is correct in principle. What specifically should constitute remembrance of Christ, discerning the Lord’s body, self-examination, etc. is the next crucial discussion, yet outside the scope of this article. Cf. The Westminster Assembly on the Conditions for Partaking of the Lord’s Supper.
 cf. Cornelius Venema, Review of Tim Gallant on Paedocommunion, Confessional Presbyterian Journal 3 (2007), p. 251.
 Similarly, Edward Reynolds (1599-1676), “Faith may be in the heart either habitually as an actus primus, a form, or seed, or principle of working; or else actually as an actus secundus, a particular operation; and that, in the former sense, it doth but remotely dispose and order the soul to these properties: but, in the latter, it doth more visibly and distinctly produce them.” (Three Treatises of the Vanity of the Creature, pp. 507-8; cited in William Young, Reformed Thought, p. 123).
 Theologians use multiple terms for this concept: seminal faith; seed, root, or principle of faith; habit or disposition of faith (habitus fidei); grace of faith (WCF 14.1). Cf. Richard Muller, Dictionary of Latin & Greek Theological Terms, 2nd Ed. (2017), habitus fidei, p. 146, actus fidei, pp. 8-10.
 The question of how ordinary it is that elect infants are regenerated in infancy has been a matter of debate. Most Reformed theologians tend to say, from the promises of Scripture and the Covenant of Grace, that covenant infants dying in infancy are undoubtedly saved (Dort 1:17), others prefer the more cautious language of “elect infants dying in infancy” (WCF 10:3). But with regard to covenant infants surviving to adulthood, some believe they are ordinarily regenerated from birth, others say that they are ordinarily regenerated later in life when they hear and understand the gospel, and others prefer to not say one way or the other since it can happen at any time and it is not clear from Scripture. However, all are agreed that the ground of infant baptism is the command and promise of God, not because of any presumed regeneration. For an in depth discussion of these positions see Herman Witsius, The Efficacy & Utility of Baptism in the Case of Elect Infants Whose Parents are Under the Covenant, MJT 17 (2006), 121-190.
 Later, Mastricht writes, “Regeneration conveys that power into the soul, by which the person who is to be saved is enabled to receive the offer. Conversion puts forth the power received into actual exercise, so that the soul does actually receive the offered benefits.” (A Treatise on Regeneration, p. 17 (this will likely be in the upcoming vol. 5 of his Theoretical-Practical Theology translated & published by Reformation Heritage Books); cf. WCF 10:2).