Say that it's no more distracting than having a student ask for a piece of paper to write on and then giving them said piece of paper, and that the only reason they've brought you in is because of the content on the paper, and that doing so is discrimination. That it's not based on actual distraction, it's an excuse, because of either personal bias or trying to defend the teacher that overreacted in the first place.
Explain how the teacher overreacted, again, simply because of what was on the piece of paper rather than the fact that a piece of paper was given at all, that they were looking for any excuse to get rid of you due to personal prejudice against you, and that having said personal prejudice is unacceptable. Say that without that prejudice you wouldn't be there and that it should be the teacher that's getting a talking to for discriminating against their own students.
Say how the entire situation is a gross overreaction to what is essentially an expression of freedom of speech and freedom of religion, and that the group is not actually causing any harm. If they want to claim to have those things then they need to tolerate it and put childish prejudice aside.