This is an interesting paper, which I haven't gone through completely but got a gist of it from other blog sources.

Basically the research suggests that it is no those who truly believe in God or religion who are the problem but those who use religion or God to promote their agenda, to promote their political position or to promote their career are the ones who are the trouble makers.

Hostility towards outsiders is found to be high in those people who are extrinsically motivated by God or Religion. Intrinsic motivation in God is enjoyment in praying or worshiping God but not to some external goal such as money, power or political ambition. Those who have extrinsic motivation in praying to God are the ones who cause trouble, and are xenophobic.