Both.
From a religious point of view, it's pointless to argue - you have your dogma and I have mine. We will never coinvince one another. Plus, for me personally, it's a moot point, since
****WARNING The next statement could be considered Too Much Information!!******
...the Good Lord saw fit to give me a gun armed only with blanks
***END TMI ***
Consequently, I have sex only for pleasure. Is that a sin? If it isn't, why can't others have (married) sex for pleasure as well? Doesn't Solomon's Song of Songs give the impression that such an idea was part of His plan?
OK, enough theology (like I said, we'll never agree)
Now, demographics: AppyPappy said it well - it's not quantity, it's quality. In fact, quantity without quality is extremely counterproductive (Africa? China?) Steyn is only partially right. Europe is failing not only because of low birthrates and high immigration rates - but because the Europeans left are snarky pessimists with no freedom. America is great because it is creative, innovative, full of energy. This comes from freedom . As Steyn once said: "America is an optimistic country because that's where the optimists went".
When we become secular, snarky pessimists like the Europeans, we will cease to be a great country, no matter how many people live here.