I don't like being "witnessed to" in public, and I am guessing you don't either. You were home free, then decided to prolong the conversation to talk about how he was doing a subpar job of a thing you didn't want to put up with to begin with. So now that he's heard your words, what next?

Does he get more aggressive with his pitches? Lead off the next person with a heartfelt anecdote about how he got saved instead of just asking for money? Do you think you made him a better person by prolonging it?

I just can't fathom being hit up for money by randos on the street (which is always annoying particularly when they do the "I'm a pastor just trying to . . ." angle) and then going "no, I'll teach him a thing or two, about my personal religious beliefs."