1. I've said here before that the contraception question is not one of chapter and verse, but of interpretation. Until the 1930 Lambeth Convention (Anglican--a tradition founded on divorce and now swirling down the drain with a bunch of lesbians impersonating pastors), the Church catholic considered contraception an unchaste practice. There was more ecumenical unity on contraception than there was on the sacraments. As late as the 1950s publications of the LCMS condemned contraception (then they just got quiet on the topic). Interpretation belongs to the whole church, not me and my B-I-B-L-E, and that's what the whole church understood Scripture (Onan et al.) to be saying for 1930 years (and all the time before that).
This one is really the bottom line in my personal view which, again, I can't imagine being of value to anyone. But here are a few more ways of thinking about it:
2. Imagine a pastor and his parish saying, "We've made some disciples of all nations, and we're happy with them. We're going to take care of them and enjoy our time together. If we made more we might not be able to give them everything they need. Making disciples makes us tired and sick and poor. No more disciple-making." I bet the DP would love it.
3. Christians put a lot of stock in condemning fornication on the grounds that sex and marriage go together. (Chapter and verse for that? Adultery, huh? What does "adultery" mean?) Babies and sex are connected far more inextricably than marriage and sex are. It's easy to engage in intercourse outside of marriage; you don't even have to think about it, as many hungover teenagers can testify. It is normally not so easy to engage in intercourse and not have a baby happen, as many pregnant teenagers can testify. Contraception requires planning and deliberate action; it is a multi-step process (acquisition, possession, use) that can never occur in a moment of lapsed judgment. God made it harder to separate babies from sex than marriage from sex. Little wonder we should see it the other way.
4. "But what strikes me as truly extraordinary is the implication that there is something low about the objective [of marriage] being the birth of a child. Whereas it is obvious that this great natural miracle is the one creative, imaginative and disinterested part of the whole business. The creation of a new creature, not ourselves, of a new conscious centre, of a new and independent focus of experience and enjoyment, is an immeasurable more grand and godlike act even than a real love affair; how much more superior to a momentary physical satisfaction. If creating another self is not noble, why is pure self-indulgence nobler?"
G.K Chesterton, "Blasphemy and the Baby," Brave New Family
I am mystified by the elevation of the "unitive" aspect of marital love by anyone with a sacramental confession. It's not magic. The unity is REALIZED in the literal one flesh who comes from two separate people. The rest is happy thoughts, and whatever esoteric thingy seems to be indicated in 1 Cor 6 (if some qualified person would care to explain that in the comments, I'm all ears). How can unity possibly be enhanced/increased by cutting out its fullest manifestation?
5. Would it be ethical to use some method or device to remove pleasure from conjugal relations?
6. Every marriage is an icon of Christ and his holy bride, the Church, who give themselves utterly to each other and whose love is ever-bearing. Contraception is antithetical to self-giving, other-accepting love. It introduces disintegrity to the marital union. There is ample evidence that it will not necessarily kill a marriage (although we would be foolish to disregard the correspondence between the rise in contraceptive use and divorce, however it may be interpreted), but it will compromise it. It is likely to leave one spouse feeling used, even if both want to or feel they must prevent conception. Marital love normally has a consequence which causes both partners to count its blessed cost. To eliminate the cost (actually an investment) is to cheapen the act and actors. If a baby were not the act's weightiest meaning and effect, we wouldn't be having this conversation at all.
Phew. Is it hot in here?
Single persons wishing to avoid all this trouble have an opportunity to do so by remaining celibate. To the married who feel they cannot have more children, the Church has historically held out the option of continence. The present day is not this option's most popular era. :P It is still an unnatural and disintegrative separation of three things God has bound together (marriage, marital intimacy, marital fruitfulness), but conforms to the "less un-divinely ordained" view of argument 3.
I'm going to stop typing now.