It is often argued that we should look at the composition of the Bible as we look at the person of Christ, as fully human and fully divine. Some use this analogy to emphasize the God-given nature of Scripture. Others turn around and use the analogy to assert that Scripture errs from time to time. Timothy Ward makes a different claim altogether, arguing that the incarnation is simply not a useful analogy for the inspiration of Scripture.
In fact this kind of analogy between Scripture and incarnation is of very limited value. As many writers have acknowledged, the union of divine and human natures in the incarnation is by its very nature unique, and so can be appealed to only tentatively as an analogy, and its usefulness as such will be severely curtailed. In particular the human and divine actions that in some ways interact in the production of Scripture are not usefully comparable with the human and divine natures that unite in the person of Christ. A ‘nature’ and an aspect of interpersonal linguistic action are rather different entities. (75-76)
Later Ward explains:
To say that Jesus Christ is divine is to say, in traditional orthodox categories, that in him a fully divine nature was united with a fully human nature, without separating or confusing the two. To say that the Bible is divine is appropriate and necessary, but it is to make an entirely different kind of claim, because in the case of the Bible we are attempting to describe not a person but a set of interpersonal communicative actions. To speak of Scripture as in itself divine is therefore to speak of the divine origin of the speech acts of Scripture, a characteristic that follows from their identity as God’s speech acts. To say that Scripture is divine is not to say less than this, because that would drive an unwarranted and destructive wedge between Christ and his words. Yet neither is it to say more than this, since to identify Scripture as the Word of God does not exalt in competition with the union of divine and human natures in the person of Christ. (77-78)
In other words while it is certainly true that the divine word of Scripture employed human agency, this does not mean the Bible is the union of human and divine akin to the two natures of Christ, for the simply reason that Scripture is not a union of natures. Scripture records linguistic communication of divine origin through human instrumentality. The Bible is a God-breathed book (2 Tim. 3:16) which men spoke as carried along by the Holy Spirit (2 Peter 1:21). Scripture is not a little human and a little divine. The words are from God. He simply and gloriously used men’s brains (including their personalities and styles) to get his words down on paper.
The analogy of incarnation is not the best analogy anyway. And it certainly should not be used to undermine the full trustworthiness of Scriptures.