If you guys don’t read That Married Couple, you really should! Elizabeth’s over there posting on a lot of interesting topics (from leaving the bathroom door open to apologetics!), but I was really impressed by her post today on Onan’s sin.
Its commonly known (at least in the Catholic world) that all Christians were formally, theologically against contraception until 1930, when at the 7th Lambeth Conference the Anglicans decided that it was justifiable to use contraception in limited circumstances.
Her post covers the biblical argument as well as quotes from the founding fathers of the Protestant Reformation (including Luther, Calvin, and Wesley) as to why contraception and coitus interupptus is a serious sin because being against contraception was never just a Catholic thing, it was a Christian thing.
Definitely worth checking out, as well as pondering what has changed since then.