Andrew It seems to me that this sentence should be worded: "many Catholics are against premarital sex." There is also no one Catholicism - despite common dogmas, in practice there are very different approaches to certain issues in particular churches. It all depends on the local conditions and the strength of the church in society.
Correct about the sentence. My point about the wording is that it's hard to discuss something when the sentences written don't correctly state what the writer has in mind. Of course no one can expect a person to write clearly in a language not their own.
I don't know what "many" means in "many Catholics are against premarital sex". I do know the pastor in our parish complains, from the altar, that there are not enough weddings in our parish given the size of it. Is there less sex than before? Doubt it, but there are less weddings. Perhaps in Spain, e.g., "many" means lots of Catholics but I don't know. Just as you say it depends on the locality.
Andrew And in Poland, it is very difficult to buy any contraceptives other than condoms, because the Church (through its faithful) has a direct influence on legislation and thus tries to make access to them as difficult as possible.
It used to be so where I live near Boston. No longer, it seems. I think the local child molestation scandals in the church made people tired of being preached to about morality. That and a general loosening of attitudes. If you are young and your Protestant friends are doing it methinks it's more likely you will to.