Is faith an irrational leap in the dark, or a rational trust in the evidence?

At first glance, Romans 4.18-25 seems to answer both ways. Here’s what Paul wrote:

Against all hope, Abraham in hope believed and so became the father of many nations, just as it had been said to him, “So shall your offspring be.” Without weakening in his faith, he faced the fact that his body was as good as dead-since he was about a hundred years old-and that Sarah’s womb was also dead. Yet he did not waver through unbelief regarding the promise of God, but was strengthened in his faith and gave glory to God, being fully persuaded that God had power to do what he had promised. This is why “it was credited to him as righteousness.” The words “it was credited to him” were written not for him alone, but also for us, to whom God will credit righteousness-for us who believe in him who raised Jesus our Lord from the dead. He was delivered over to death for our sins and was raised to life for our justification.

The background of this passage is Genesis 15.1-6, in which God promised a childless Abraham that he would nevertheless father a child. According to Genesis 16.1-4, when Abraham and Sarah were unsuccessful in producing a child, Sarah suggested that Abraham father a child with her Egyptian maid Hagar, which Abraham proceeded to do. But this child, Ishmael, was not the child God had promised. So, in Genesis 17.15-22, God reiterated the promise that Abraham and Sarah would produce a child, even in their advanced old age. The birth of Isaac in Genesis 21.1-7 at last fulfilled God’s longstanding promise.

With this biblical background in mind, you can see why some people view faith as an irrational leap in the dark. It is a simple biological fact that post-menopausal women like Sarah simply do not get pregnant. Nevertheless, Paul wrote, “Against all hope, Abraham in hope believed.” Hoping when there is no hope seems to be irrational.

And yet, Abraham very rationally took into consideration the overwhelming power of God. According to Paul, he was “strengthened in his faith and gave glory to God, being fully persuaded that God had power to do what he had promised.” In other words, Abraham’s hope-against-hope was built around the entirely rational premise that the God who created the world out of nothing has the power to create life in a barren womb too. In our day and age, medical doctors have been able to induce pregnancies in women well past their child-bearing years. Doesn’t it seem a bit foolish to deny that Almighty God might have the same ability?

So, faith, which seems a bit irrational in the beginning, turns out to be a very rational response to the promises of an all-powerful God. That God created us, and through Christ, he is saving us. Do you trust him? It seems like the only rational thing to do.