Talk about politics, your hobbies, your interests, your favourite things but don’t talk against someone’s religion. It hurts and it’s unethical. If you do this then change yourself. This world is already full of negativity, bring some love and positivity in yourself and in this world.
I think Ayaan Hirsi is a good example of when one ought to be critical of religion. She comes to the table with good reasons, not just mean words (which, for some people online, seems to be a kind of currency).