…afterwards, for the better preserving and propagating of the truth, and for the more sure establishment and comfort of the Church against the corruption of the flesh, and the malice of Satan and of the world, to commit the same wholly unto writing (Prov 22:19-21; Isa 8:19-20; Mat 4:4, 7, 10; Luke 1:3-4; Rom 15:4); which maketh the holy Scripture to be most necessary (2 Tim 3:15; 2 Pet 1:19); those former ways of God’s revealing his will unto his people being now ceased (Heb 1:1-2).

Westminster Confession of Faith 1:1

Edward Leigh, A Treatise of Divinity, I.viii, pp. 135-138.

In respect of the substance thereof it was always necessary; in respect of the manner of revealing it is necessary since the time that it pleased God after that manner to deliver his word, and shall be to the worlds end. It is not then absolutely and simply necessary, that the word of God should be delivered to us in writing, but only conditionally and upon supposition. God for a long time, for the space of 2400 years, unto the time of Moses did instruct his Church with an immediate living voice, and had he pleased still to go on in that way, there had been no necessity of Scripture now more then in that age, there was a continual presence of God with them, but now there is a perpetual absence in that way; and the word of God was written.

1. For the brevity of mans life. See the 5th and the 11th chapters of Genesis. The Patriarchs were long lived before, and after the Flood to the times of Moses they lived some centuries of years; therefore afterward the purity of the word could not fitly be preserved without writing. By writing we have the comfort of the holy word of God, which from writing receiveth his denomination, in being called Scripture: which is nothing else but writing.

2. That the Church might have a certain and true rule and Canon, whereby it might judge of all questions, doubts and controversies of Religion (Luke 1:4). Every mans opinion else would have been a Bible, and every man’s lust a Law.

3. That the faith of men in Christ which was to come, might the better be confirmed, when they should see that written before their eyes which was done by the Messiah, and see all things that were foretold of him verified in the event.

4. That the purity of God’s worship might be preserved from corruption and the truth propagated among all Nations.

5. To take off excuses from men that they did not know (Rom. 10:18); civil laws are written and published that offenders may be excusable.

The Penmen had a command from God.

1) A public and outward command, as Jeremiah (30:2; 36:2), Moses (Exod. 17:14; 34:17), and John was commanded 12 times in the Revelation to write (Rev. 1:11; 2:1, 8, 12, 18; and 3:1, 7, 14; and 14:13; and 19:9; and 21:5).

2) An inward command by private inspiration and instinct (2 Peter 1:21).