First off, this website gives some statistics on US major religons:
World Religions Religion Statistics Geography Church Statistics
So it is not a question that the majority of the United States belongs to some form of a Christian religion. This is not so true in many other countries throughtout the world, for example, here:
BetaVote.com
We all know that George "W." Bush is a Christian president, and where did the majority of his votes comes from? Christians.
Bottom line. It is to the candidates advantage to associate themselves with a prominent US religion. Especially Christianity. Unfortunately, that is how the game is played here.
Seriously, though, you know we're doomed when a candidate says, "We are winning the country back for God" or "God is with America". To them I say, "BS" :rolleyes:
And to voters who will only vote for a president that shares their religious views...I shake my head.