I agree with the first part, that they think sex is reserved for procreation, and that anything else is immoral, but there's a more cynical view of that latter.

I think there's lots of room to be cynical, here. But some religious faiths have pretty consistently been opposed to abortion, like the Catholic Church since about the 1st Century:

en.wikipedia.org - Catholic Church and abortion

...and even for those denominations of Christianity that have come somewhat later to that conclusion, there's still also room to allow for our growing knowledge of human development to play a role as well. After all, that's also around the time we first began to get a good understanding of embryology and fetal development - mid-19th century or so. Prior to that, we didn't really know what was going on in there. After that, it suddenly became very possible - and very difficult - for religious leaders to deal with specific questions about what was going on inside a pregnant woman at exactly which point in their pregnancy. It becomes much, much hard to argue that human "ensoulment" occurs at exactly 40 days (or whenever) as older philosophers and traditions had held once you know exactly what's happening to a fetus at day 35 and day 45 and day 55.

But if you want to be really cynical, you might note that organized evangelical opposition to abortion really didn't get started until the 1970's or so. Which supports an argument that their opposition is more motivated by politics than money - or at least, back then. But having now firmly inculcated their supporters with a belief that human life (and ensoulment) begins at conception, many (most?) of those opponents have grown up with that belief being taught to them all their lives - and have a least come by that precept honestly.