(Abraham)...who, contrary to hope, in hope believed, so that he became the father of many nations, according to what was spoken, “So shall your descendants be.” And not being weak in faith, he did not consider his own body, already dead (since he was about a hundred years old), and the deadness of Sarah’s womb. He did not waver at the promise of God through unbelief, but was strengthened in faith, giving glory to God, and being fully convinced that what He had promised He was also able to perform. (Rom 4,18-21)

In describing the long years that preceded Isaac's birth, it does not seem to us that Abraham had the kind of faith evidenced in the Epistle to the Romans. We see in him, indeed, glorious victories, but also many hesitations and defeats. Therefore, the attitude described in the Epistle to the Romans was obviously only a matter of the final conclusion of the 25 years of discipleship. He had grown to this faith, he had worked his way to it through the various situations and trials through which he had passed. It is impossible to pigeonhole Abraham as a biblical figure: since he is called the father of faith, he always believed, did not doubt, and that´s it. This is a complete misunderstanding. Like everything that has value in life, his faith was dearly paid for; he had to drudge his way to it, to put it succinctly.

But in the end, this man permanently undergoing a change of heart and character rose to his height. Then, when it was much harder than ever before! Before, he could have had the child after all, at least in theory, the problem was Sarah's infertility. But when his body (and Sarah's body) went limp and the "biological clock" caught up with them both, all hope was over.

What a strange power the faith has to turn the impossible into the possible. And how marvelous that Abraham actually grew into it when he now faced far greater obstacles than before. At the time when things were easier, he wavered in his faith (he became satisfied with Ishmael). Now that he had grown old and believing was so much harder, even impossible - he believed God and strengthened by faith "gave honor." At that moment, he not only believed, but also spoke. Never before had he seemed so deranged to his servants as when they saw him, the centenarian, walking through the camp, praising God and expecting the birth of a son he clearly could no longer have.

To conceive him, he and Sarah had to experience the revival of what was already dead in their bodies. God´s personal promise to Abraham came to fruition as a resurrection, life from the death. The life of Isaac was a miracle, a revelation of things of divine character on earth, the beginning of the nation of God that was to become the light of the world. And therefore he had to be conceived by faith, not in the normal way - he had to come "from above," to be called into being by the movement of God and to be surrendered and consecrated to Him.