After his “my Muslim faith” slip to George Stephanopolous, nothing could have ever made me believe that he’s a Christian, but as it is almost his every subsequent action has underscored that he’s a Muslim.
The only way a person could say “my Muslim faith” while meaning to say “Christian” is if he was actually thinking the truth and it inadverdantly slipped out. Neither myself, nor any Christian I know, would ever make that particular “slip”, it just wouldn’t be the natural word to come from our lips when talking of our Christian faith.