Just because the belief system I believe includes some beliefs that some other belief system has, doesn’t mean I’m like, taking portions from that other belief system.

(If you think that Christianity says that the purpose of people is purely to reproduce, you are quite mistaken.)

The purpose of people is to be in loving relation with God, and with each-other. The purpose of coitus is to further those goals, by symbolism, by strengthening affection among a married couple, and by producing more people.

And the purposes of sexual desire follows from these purposes.

(To justify the claim that Christianity does not say that coitus should only ever be done with the goal of reproduction: If one burns with desire, it doesn’t become not right to marry on account of being infertile. Now, I think one should be open to the possibility of a child, and be willing to raise a child if need be, but it doesn’t need to be the goal of the marriage.)

Of course, I recognize that some people reject the idea that there are purposes to these things / reject that there is a telos to things. I don’t think either I nor they will convince the other in this thread.