Abstinence programs are popular with Christian Right: if sex is going to be mentioned in schools, it's only going to be mentioned in a manner that discourages it. It's been revealed, though, abstinence programs end up teaching all kinds of lies and myths in order to get the message across. Perhaps some conservative Christians honestly don't recognize these lies for what they are, but I strongly suspect that some also don't or wouldn't care.
It's been made quite clear by some that abstinence-only sex education is about ideology, not about practicality. They don't support this sort of program because they believe it works better than the alternatives, works well, or even works at all. They would support such programs even if it were shown (and it has been) that they don't work because abstinence-only programs are the only ones consistent with their own religious ideology. So if a failed program is worth supporting, why not a lying program?
This, however, undermines the very point of a secular, liberal arts educational system. Teaching lies as well as truths -- and not caring about the difference between the two -- is characteristic of ideological indoctrination, not education. It's something one might expect to find when studying the school systems of totalitarian governments, like in Germany under the Nazis and the Soviet Union under communism. Funny how those two are consistently associated with atheists by the same conservative Christians who have no compunction about using similar standards when it's their own ideology that might benefit.
What sort of sex education program do you suppose Bristol Palin, daughter of Sarah Palin (John McCain's pick for Republican Vice-Presidential nominee) was exposed to?