Sure!
McCain was asked if he thought a non-Christian should be president of the United States. He answered, "I just have to say in all candor that since this nation was founded primarily on Christian principles, personally, I prefer someone who has a grounding in my faith." I have a big problem with religion being used as a basis for the decisions our President makes. For instance, I don't like the idea of creationism being taught in schools. I don't think public school is the place for religious teachings.
McCain has stated that he believes human life begins at the moment of conception and that embryos should be afforded full human rights. McCain has said he supports amending the U.S. Constitution to ban abortion, except in cases of rape, incest, or risk to the mother's life. I do not agree with his stance on abortion at all.
McCain is against federal funding of birth control and sex education; his opposition included a vote against spending $100 million to reduce teen pregnancy by education and contraceptives. McCain voted in 2003 and 2005 against legislation requiring insurance plans that cover prescription drugs to also cover birth control. I don't think the government should be able to have that kind of control over the perfectly sensible option of birth control.
He supported the failed 2006 Arizona initiative to ban gay marriage, and supports a similar initiative in California that will be on that state's November 2008 ballot. He also voted in favor of the Defense of Marriage Act of 1996 which barred the federal government from recognizing same-sex marriages. I believe any two people should have the right to marriage no matter what their gender or sexual preference is. I'm not thrilled to death with Obama's position on this issue, but at least he has no issues with a civil union.
The above issues are make-or-break for me. I will not vote for a candidate who would support state-sanctioned religious teachings in school, is anti-abortion, anti-birth control, and anti-gay unions. Palin is even further along the path of what I won't support.