Rev. Graham must have had the Devil in him at that moment. It happens to the best of us.
I think that sometimes very saintly people are so good that they can be deceived by the extremely polished and wicked among us. When you are good, you do not think ill of anyone. Reverend Graham has been deceived by these professional liars as many another good person has been. It doesn’t mean that the Devil was in him, just that he is old, gentle, and perhaps easier to fool now.