The modern instinct is to treat sex as a private matter that is of no real consequence to the body politic, and thus no legitimate concern of the sovereign, or of the public. Against this conservatives argue that sex has all sorts of important consequences for the health and welfare of the body politic, whether demographic, epidemiological, economic, pedagogical, or cultural, so that sexual morality matters to the polis a very great deal, and is therefore a fit concern both of the sovereign and the people.
These sorts of pragmatic objections to liberal social and sexual mores do tell, of course, and heavily. But they don’t begin to get at the immense importance of sex in the long run – the really, really long run, under which the whole history of the universe is like an evening gone.
The ultimate end of sex – which is to say, the true end of sex - is the actualization of human souls in the lives of immortal persons who by virtue of their very existence have the option of enjoying forever the Beatific Vision, and the endless other beauties of Heaven outside the throne room. Each life that succeeds to Heaven represents an infinite increase in the realized value of Creation. A forgone human life then represents an infinite cost to the whole economy of Heaven, forever and ever. Being himself infinite, God can of course cover that defect of creaturely perfection with no problem; but for all the other citizens of Heaven, the failure to implement a single tiny life is a catastrophic injury to the wealth of glory they might have enjoyed, had the imperfection of procreative potential implicit in creation ab initio never occurred.
I pray that all three of my kids get into Heaven, so that if I am able to join them there we can all enjoy each other forever. If that works out, I shall be happy indeed. But I might have had six children, or more. If I had, and if the whole family had got to Heaven, think how much more wonderful it would have been for us, all – in worlds of worlds, to everlasting and everlasting!
Sex is the way God has arranged to generate gods. For all Christians, then, it’s a really big deal, almost the best thing there is.