There are a lot of non-spiritual reasons being serious about religion could strengthen a relationship (in this era, being a "regular attender" is a signal of se

There are a lot of non-spiritual reasons being serious about religion could strengthen a relationship (in this era, being a "regular attender" is a signal of seriousness; in the 50s, maybe not.) It's a shared interest/passion that both people are investing time into, both can participate in, and both can discuss. It gives the couple a lot of friends in common, and a circle of social support. It connects younger folks with older mentors and positive role models -- if your primary childhood example of marriage was a crumbling parental relationship, but you joined my grandparents' church and got to see them interact on a weekly basis, you might develop healthier relationship habits. And yes, it places a stigma on divorce -- and places a huge emphasis on the importance of marriage, so in a way it's like attending a marriage seminar on a regular basis. Even a religion without any "supernatural" or "unseen" value would still very likely have these effects.