Did you notice I specifically said “polite?”
If they were rude, or loud or abusive, you had every right to become offended. I’ve never met a Mormon missionary that behaved in this way, but given the number of them out there it would be very surprising if there weren’t some.
But, IMO, you should have considered the rudeness or loudness or abusive language to constitute the verbal attack, not the disagreement.
YMMV, of course.
If they were rude, or loud or abusive, you had every right to become offended
Are the evil words not enough ???