I had a similar incident with the LDS.
We were (very politely) approched by and exceedingly clean cut Mormon who asked us if he could talk to us about his religion.
I suggested that he was wasting his time, as I'm an atheist and my better half is a Catholic.
He spend 10 seconds talking to her, determined that she was an active practising Catholic, and proceeded to ignore her for the next 30 minutes while he dug himself into a hole with Old Testament Inerrancy.
I think that was the first time I'd discussed religion with anyone in about a year - it doesn't come up as a day to day conversation.
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