Genesis 21 is the hinge of the Abraham cycle. For twenty-five years Abraham and Sarah have been carrying a promise that their bodies kept contradicting. Moses is writing for a people who know what it is to wait on God past the point of plausibility — Israel in the wilderness, Israel in exile, Israel under Rome. The narrator's repetition is deliberate: as he had said... as he had promised... at the time of which God had spoken. Three times in two verses the text insists that what just happened is simply God keeping his word. The miracle is not the baby. The miracle is that God speaks and then does.

From the writers we read together

David Berlinski

secular Jewish mathematician and philosopher, author of The Devil's Delusion

Berlinski is not a believer, which is precisely why he is useful here. His project has been to dismantle the cultural confidence that science has closed the door on the miraculous. He points out, again and again, that the regularities we call natural laws are descriptions, not prohibitions — and that the universe's deepest features (its existence, its intelligibility, the appearance of life, the appearance of mind) are exactly the kind of things a closed materialism cannot account for. Sarah's son is, by every actuarial measure, impossible. The text knows this. It has Sarah laughing about it. Berlinski's contribution is to remind a modern reader that the laughter is not naive; it is the right response to a closed world cracking open.

What Genesis 21 asks is whether you will let the door stay open in your own life. Most of us have learned to manage disappointment by quietly narrowing what we expect God to actually do. We will affirm that he could; we no longer expect that he will. Berlinski's secular skepticism of skepticism is, oddly, a help here. If even an unbelieving mathematician will not concede that the universe is closed, the believer has no business living as if it were. The God who visited Sarah at the time he had spoken still keeps appointments. The question is whether you are still listening for the date.