It seems much more appropriate to write "Islam doesn't teach people to be corrupt. Corruption is a function of poverty, not religion. For example countries of religion X aren't islamic but report similar signs of corruption." Calling people bigots seems less appropriate and counter productive.

Someone who makes even a rude assumption about a people isn't necessarily a bigot. They could just be wrong and you could correct them without insulting them in the same you would hope people would correct you if you said something inaccurate.