I wonder if the mid life crisis is a completely modern and secular malady. Thinking to my religious friends who have 5+ kids, a rich spiritual life and deep engagement with community, it's very hard to imagine them going through one. Because they are too busy, but mainly because their life is oriented from the get-go around what is very meaningful to them
Nearing-50, non-religious person checking in here: I don't think it has much to do with religion or non-religion. I must be really lucky or really privileged because I haven't had even a hint of "crisis" that I can remember. Knock on wood that I don't catch it somewhere. Isn't the common denominator of a midlife crisis a yearning for the past? Overwhelming nostalgia? Dad buying a sports car so he can pretend to be 20…
So you see that car you have always wanted but never bought because it's impractical and expensive and say to yourself, "I don't need four seats any more, and I do have the money if I'm careful. Why not? I've always wanted it."
Of course some folks do this irresponsibly, but it doesn't have to be a fantasy about pretending to be something you used to be. Just now you can, when before you couldn't.