I love the kind of logic that flows from great faith in the Omnipotent, Sovereign God. It’s a kind of logic that seems irrational and foolish by human standards; but, to those who know and trust in the power of God, it’s the only kind of rational thinking. It’s an amazing thing to behold, and we ought to marvel at it, meditate on it, and pray that our faith might become as great. And there is no better or more powerful example of this “logic of faith” in the Bible than the case of Abraham and his response to God’s promises to him. In particular, what I want to focus on here is Abraham’s trusting God’s promise to provide him an offspring through Sarah.
In Genesis (15:1–6; 17:16–19; and 18:10–15), God promises Abraham, who is then about 100 years old (and whose wife Sarah is 90) but is without a natural son, that he will give Abraham a natural son to be his heir—a son that “will come out of your own loins,” as the Hebrew literally says. And, despite the fact that this was naturally impossible, since “Abraham and Sarah were old, advanced in years,” and “the way of women had ceased to be with Sarah” (18:11), Abraham believes and trusts God, that He will indeed provide a Son for him through Sarah. And so, one year later, “the Lord visited Sarah as he had said, and the Lord did to Sarah as he had promised” (21:1), and Sarah thus gave birth to a son, whom they named Isaac.
But, although the event is recorded in Genesis, what I want to focus on here is what Paul says about Abraham and his great faith, in Romans 4:18–21. Paul says:
18 In hope he [Abraham] believed against hope, that he should become the father of many nations, as he had been told, “So shall your offspring be.” 19 He did not weaken in faith when he considered his own body, which was as good as dead (since he was about a hundred years old), or when he considered the barrenness of Sarah’s womb. 20 No distrust made him waver concerning the promise of God, but he grew strong in his faith as he gave glory to God, 21 fully convinced that God was able to do what he had promised. (ESV)
We see the logic of faith beginning in verse 19. Abraham “considered” his situation. But what was there to evaluate? Ninety-year-old women can’t have babies! They’re barren—infertile! Yet Abraham, although fully cognizant of this impossibility, remained “fully convinced that God was able to do what he had promised.” In fact, his faith actually grew stronger as the situation became more obviously impossible. In the reasoning of the natural (i.e., non-Christian) man, who does not know the character of God, conception for Sarah is an absolute impossibility. The logic of faith, however, always holds as an unshakeable and overriding premise the omnipotence and faithfulness of God, so that no amount of apparent evidence to the contrary matters. If God has promised something, he will never fail.
The object of Abraham’s faith, moreover, was God himself. Abraham believed the promise because he recognized the ability and the trustworthiness of the promisor. And, by trusting in God, Abraham was glorifying God (v. 20). This is not because Abraham was making God glorious or adding to God’s glory (blasphemy!), but because Abraham was showing God to be what he really is. He was acknowledging the reality of God’s character and the reality of the situation. Abraham acknowledged the truth that he himself was totally unable to produce a son and heir and that only God—“who gives life to the dead and calls into existence the things that do not exist” (v. 17)—was able to do it and would do it.
Oh, that we might live according to the logic of faith as Abraham did! May God grant us such a faith.