Q - I have some friends who understand and agree with the church's teaching on abortifacients (chemicals that cause abortions as the birth-control pill can), but do not agree with its stance on barrier methods of contraception. Our main argument revolves mostly around the use of condoms. I think the basic disagreement is whether there is a dual purpose behind sex: as both bonding and procreative. I bring up this point and we tend to stalemate. Could you explain the history of Christian teaching on contraceptives and also the logic behind the duality of purpose for sex that the church teaches? If you can reference the specific example I always get of whether a barren couple's marriage would be considered valid, I would appreciate it too. My friends are not Catholic, so Biblical references would be better than Church documents in this case.
A - Thanks for the question. First of all, as I always do, I want to remind you that the point of dialogue with another is not to "win", but to propose what the Church teaches. So, while I will help answer your questions, it isn't meant to be to give anyone ammunition to fire away.
The logic is simple behind while God intended there to be two purposes to sex, the procreative dimension (babies) and the unitive (bonding). The simple reasons are that God wants us to perpetuate our species and do so with love. Sex is a deeply spiritual exercise. It brings a man and wife closer than anything else could. When the end result is having a baby, then both purposes of sex are accomplished. Anything that would intentionally take either purpose out of the sexual act makes it into something it wasn't intended to be.
In this line of reasoning we can see why contraception is wrong. It is an intentional act of saying that we do not want the gift of fertility that God has given us. This is not a Biblical way of thinking about sex. In the Bible fertility is thought of as a blessing and to be infertile was a curse. In today's society we see children as the curse that we guard against.
The difference with an infertile couple is that they do not intend to be infertile. Therefore, they are not intentionally taking one aspect out of the sexual act.
For more on this topic, you can read a longer post I did a while back.