Shedding presuppositions about God, one could, after all, just as readily imagine the character of a deity to be in favour of people having sex for reasons of love and joy – not merely for procreation – as one can presently imagine that he is a stern puritanical killjoy, passionately poised in opposition to ‘meaningless’ sexual delight.
An interesting thing to know would be how many atheists would not be atheists; how many in fact would at least be agnostics, if they were to be informed that, actually, God rather likes sex, and likes humans having it too.
Not, of course, that I wish to speak for God (presuming he exists, of course) regarding what he actually thinks about sex, and what we should do regarding it. But I am aware that at least a certain degree of anti-theism is motivated by contempt for received understandings of God’s anti-sexual stance. And one doesn’t have to be particularly intelligent, I hope, to realize that you cannot with much success argue the non-existence of something just because you dislike certain of its purported characteristics.
Not that this in-itself means that God exists, of course.
Personally, in my Universe, there’d be both God and Sex, and everything would be joyful. While I have time for the dialectic, I prefer it to operate within an ambience of love.