Barak Obama made a speech about the way that religion has been used in American politics to divide rather than unite:

Barack Obama, the Illinois senator aiming to become America’s first
black president, has accused evangelical Christian leaders of
"hijacking faith" and politicising religious beliefs in an effort to
divide the country.

In a daring speech before a packed church convention,
he said the powerful religious Right had exploited its stance on
abortion, same-sex marriage and creationism to attack the Democrat
Party.

"Somehow, somewhere along the way, faith
stopped being used to bring us together and faith started being used to
drive us apart," he told the national meeting of the United Church of
Christ, the liberal church of which he is a member.

"Faith got hijacked partly because the so-called leaders of the Christian Right are all too eager to exploit what divides us.

The power of religion to divide is not a new observation, of course. Emo Phillips:

I was walking across a bridge one day, and I saw a man standing on the
edge, about to jump off. So I ran over and said "Stop! don’t do it!"
"Why shouldn’t I?" he said. I said, "Well, there’s so much to live
for!" He said, "Like what?" I said, "Well…are you religious or
atheist?" He said, "Religious." I said, "Me too! Are you christian or
buddhist?" He said,
"Christian." I said, "Me too! Are you catholic or protestant?" He said,
"Protestant." I said, "Me too! Are you episcopalian or baptist?" He
said, "Baptist!" I said,"Wow! Me too! Are you baptist church of god or
baptist church of the lord?" He said, "Baptist church of god!" I said,
"Me too! Are you original baptist church of god, or are you reformed
baptist church of god?" He said,"Reformed Baptist church of god!" I
said, "Me too! Are you reformed baptist church of god, reformation of
1879, or reformed baptist church of god, reformation of 1915?" He said,
"Reformed baptist church of god, reformation of 1915!" I said, "Die,
heretic scum", and pushed him off.