I've seen theists explain why they're theists and be well-received for it. Actual attempts at conversion tend to end badly -- the community interprets them as disruptive and broadly equivalent to trolling -- but they're also very rare.

Based on this pattern, I'd say the right clothing metaphor would be neither black nor a clown suit, but something more along the lines of wearing a thawb and matching headdress in the US or western Europe: quaint, exotic, interesting, and vaguely backward and threatening in stereotype if not in reality.