Actually, I have heard several times him saying he is a Christian. But not a single shred of evidence where he ever admitted that he follows the teaching of islam(my brothers fiancé is actually Islamic and he's a Marine so I'd appreciate no hate speech towards that faith). I'm not trying to get a rise out of you. Just would like to know where you heard.
Emails obviously do not count because that is not a credible source.
Also, just throwing it out there, America was never a "Christian Nation", but a free nation. Built on ideals of freedom, which includes religion. The majority of early settlers were Christian, but America was not invented as a Christian nation(many of the founding fathers had renounced their faith in order to cut all ties to Britain).