A majority of self-described atheists are politically liberal, while most Christians, including evangelicals and Protestants, are conservative, according to a new Pew Forum survey.

Some 51 percent of atheists and those described as agnostic told Pew that they are liberal, with 32 percent moderate and 13 percent conservative. Survey analysts said that the atheists lean Democratic because they are generally younger and agree with the party's embrace of sexual issues such as abortion, gay rights and same sex marriage.

Not so with Protestants and Evangelicals. Some 48 percent of Protestants and 65 percent of evangelicals call themselves conservatives and don't support same sex marriage and abortion.

Catholics, however, break from evangelicals and Protestants in the Pew survey. They split politically, with the most, 42 percent, calling themselves moderate, and majorities supporting abortion, homosexuality, and same sex marriage.