Because these people are in a "war" mode. They're patriotic, and altruistic, and they're concerned about being seen as a "Good Person" in the eyes of God and their neighbors. And their pastor, who they're told is the voice of the church, says what is a sin and what is not. And the pastor says abortion is a sin. Perhaps a necessary evil, but a sin nonetheless. And they are in a war with the other party, so their pastor says. The people on the TV (and not any Ted Turner Communist News Network, no sirree) tell them that this is a war on Christians and Christianity and the good moral values this country was founded upon. And even though they're not going to actually die, the "good people" believe that they must be seen fighting the good fight. So the townspeople vote as if they were predestined, and as if they were rich people, which by rights they should be anyway.

That's why people vote Republican and shoot themselves in the collective foot. :|