Reagan is the guy who made an alliance between the Christian "Moral Majority" under the leadership of Jerry Fallwell, in order to secure the Presidency. He recognized then that without the Christian right. no Republican had a chance to be elected President, ever again.
He promised a "family values" agenda which would be anti-abortion, anti-gay rights, and uphold Christian values. Once elected, Reagan forgot all about the "family values" agenda. He didn't legislate against abortion, or try to get prayer back in the schools. He tried to cut food stamps by tightening the income requirements, and the school lunch program. Cutting food stamps was a failure because his programs created so many more poor, that by the end of Reagan's first term, food stamp useage had doubled.
Republicans have been pandering to the Christian right ever since, and other than supporting DOMA and other measures restricting abortions, many of which fail to pass muster with the Supreme Court, abortion is still legal, and now gay marriage is as well. Despite being screwed over by Republicans, time and time again, the Christian right continues to vote Republican because the Democrats refuse to accept their restrictive social agenda.