I posted this on a forum today. I didn't want to lose it and it said what I wanted to say. So here it is:
A contraceptive act is not a marital act. That is the point. Let's say we have a couple who was objectively infertile (let's say wife is post ovulation for the month.) Said couple engages in an act using their sexual organs. (For the sake of argument the act is either vaginal intercourse with a condom or an act of oral copulation to male orgasm.) The point is the act itself is not the marital act!
It doesn't matter if the end result was a baby or not. It matters that the act itself was not the marital act. The point the Church is trying to make is that contraception changes marriage! These couples are seldom, sometimes never engaging in the marital act! The marital act is a procreative, unitive act. It is on this foundation that the Church condemns all forms of contraception (including oral sex to male orgasm,) all forms of IVF, and all homosexual acts. They are not the marital act. Further, it even shows why fornication and adultery are condemned. They are also not the marital act since they lack marriage!
If the 20th century showed us nothing else it showed us that having "fake" sexual activity makes for really bad bonding. Couples who engage in authentic marital acts each and every time have a much higher tendancy to stay married.
As has been said by people smarter than I. The biggest error in this debate is by starting wih the result: children, and working backwards. We must begin at the foundation of society: marriage. As we know the original family is a marriage.
