"I agree with what he's saying, but not how he's going about saying it"
And it has begun. I know exactly what comes next; it's happened before. Why didn't I see him?! All this could have been avoided had my idling brain registered the overenthusiastic howlings and frantic arm-waving earlier; I could have taken the other route, or hurried her past... but no, it's too late for that.
Deploy countermeasures! "Look, they have a sale on!" "We'd better get back, the parking ticket runs out soon..."
...To no avail. The crowd separates. The pigeons pecking at dropped chips look up, and flee to the gables of the surrounding buildings. The chap down the street playing the accordion and kicking his dog so it barks in time with the music falls silent. The unsuspecting preacher falters as the air goes cold.
With a determined look on her face, she approaches the man. Theological warfare has been declared.
By now, all hope of avoiding the situation is gone. I pretend to pay no attention; I sidle away towards an electronics shop or some other distraction in an attempt to sever any link for passers-by to follow.
I don't follow the argument. I try to avoid hearing it, if at all possible. I suppose I could watch for the comedy value, and perhaps take pride in her overwhelming reasonableness when the preacher is reduced into submission. She's one of those people who know exactly what they believe in, can accept that other people don't believe the same, and don't try to coerce anyone into changing. The frustrating thing when you're on the opposing side of the argument is that she's right...
I gave up arguing religion long ago; it just didn't seem worth it. No-one changes their faith just on another person's point of view, however loudly they rant at you. The end result is always a frustrating stalemate for both sides. That doesn't strike me as a good way for the message to spread. But then, I'm not the one in the middle of the street, spreading the word.