In this thread various posters opine that they think Christianity is polytheistic. http://boards.straightdope.com/sdmb/showthread.php?p=11897001#post11897001
They do this with the anonymity of the internet and in my opinion it is nothing but trolling to stir up religious quarrels. Religious quarrels are, as has been pointed out, dangerous and deadly. They should not be instigated simply to amuse oneself, divide one’s enemies or for other reasons.
Christianity is a monotheistic religion. Nobody within the religion contends that there is more than one diety, and the only outsiders who contend otherwise are ignorant, which may be forgiven, or trying to stir up religious quarrels for their own purposes.
Such misrepresentation of a religion is disgusting and the people who do it beneath contempt.