The three words -- immediately corrected -- were during an exchange with ABC's George Stephanopoulos on "This Week," when he was trying to criticize the quiet smear campaign suggesting he is a Muslim.
The exchange came after Mr. Obama said that Republicans are attempting to scare voters by suggesting he is not Christian, which McCain campaign manager Rick Davis said was "cynical."
"Let's not play games," he said. "What I was suggesting -- you're absolutely right that John McCain has not talked about my Muslim faith. And you're absolutely right that that has not come."
Mr. Stephanopoulos interrupted with, "Christian faith."
"My Christian faith," Mr. Obama said quickly. "Well, what I'm saying is that he hasn't suggested that I'm a Muslim. And I think that his campaign's upper echelons have not, either. What I think is fair to say is that, coming out of the Republican camp, there have been efforts to suggest that perhaps I'm not who I say I am when it comes to my faith -- something which I find deeply offensive, and that has been going on for a pretty long time."