I think a lot of the folks who try to legislate morality with abortion and homosexuality often times have a type of "representative theology." By that I mean, in politics we are a consitutional republic, not a direct democracy. We elect people to vote the issues we share, to work FOR us, represent us, in the senate, house, state level, etc. Same with president.
But with these moral imperatives, we as Christians are called to get out there and stop abortion by witnessing to the faith to individuals considering abortion. We are to get out there and help women at shelters, our neighbors, and to try to fund and support those alternative clinics that help disenfranchised women. But instead of doing these hard things, we can just elect a guy in the house, senate, or presidency to do it for us. To me, that's a bit of a cop-out. Armchair Christianity. Same with the gay stuff. You can't legislate it, you have to preach against it, witness against it, raise your kids against it, and stand up to society on your own and with your church and like-minded people. Rolling up our sleeves and doing this stuff ourselves isn't easy. Having a representative do it feels easy. But in the end, even these passionate pro-life Republicans, imho, use these social issues as wedge leverage to keep people in their camp while corporate greed, power, and control are the real issues these cats care about.