Barack Obama. - File photo image:28508:1::0

"At every opportunity, they've told evangelical Christians that Democrats disrespect their values and dislike their church, while suggesting to the rest of the country that religious Americans care only about issues like abortion and gay marriage, school prayer and intelligent design."

Obama is a member of the United Church of Christ, one of the most liberal mainstream Protestant churches, and has been accused by conservative Christians of "unbiblical" beliefs. He has opposed a constitutional amendment intended to make gay marriage illegal, and believes that any legislation should be up to the individual states.

The United Church of Christ was the first to ordain a minister who was openly gay, and endorses the right to marriage between people of the same sex.

There is a real possibility that his liberal stance on such issues, and his criticism of the Christian right will cost him dearly in the polls. As a black man who already has that handicap against him, his stand is particularly courageous. He is currently trailing Hillary Clinton, 21% to her 33%, and this speech might put him even further behind. It's a question of whether Democrats value honesty and plain-speaking enough to support him.