The books of Scripture were written by the instrumentality of men, and the national and personal peculiarities of their authors have been evidently and freely expressed in their writing, and their natural faculties, intellectual and moral, as freely exercised in their production, as those of the authors of any other writings.
Nevertheless these books are, one and all, in thought and verbal expression, in substance and form, wholly the Word of God, conveying with absolute accuracy and divine authority all that God meant them to convey, without any human additions or admixtures.
This was accomplished by a supernatural influence of the Spirit of God acting upon the spirits of the sacred writers, called "inspiration;" which accompanied them uniformly in what they wrote; and which, without violating the free operation of their faculties, yet directed them in all they wrote, and secured the infallible expression of it in words.
The nature of this divine influence we, of course, can no more understand than we can in the case of any other miracle. But the effects are plain and certain--viz., that all written under it is the very Word of God, of infallible truth, and of divine authority; and this infallibility and authority attach as well to the verbal expression in which the revelation is conveyed as to the matter of the revelation itself.
A. A. Hodge, The Westminster Confession: A Commentary, p. 33-4