Some might think that Romney lost evangelicals because he wasn’t Christian enough. I think it’s the other way around. He acted too Christian.
Romney believed that to win the nomination he had to win over evangelical Christians. He figured the way to do that was to get all Jesusy. So he declared, “I believe that Jesus Christ is the Son of God and the Savior of mankind.” In so doing, he showed a fatal misunderstanding of the attitude of evangelicals toward Mormonism. Though some evangelicals do believe Mormonism is an evil cult, many simply believe it’s an odd religion. Strange, but no stranger than all sorts of other religions. These evangelicals are actually quite tolerant, and would be willing to vote for a non-evangelical candidate who shared their values in other ways. Remember how popular Joe Lieberman, an Orthodox Jew, was with evangelicals? Many Christians at the time simply said, well he’s not of our faith but he’s religious, the next best thing to being a religious Christian, and he’s got conservative values.
Of course Romney was in a difficult position. Mormons do consider themselves Christian. So he was faced with the dilemma of alienating evangelicals and betraying his own faith.