Everyone should be able to express their opinions on anything they want. If you want to say that someone else's culture is stupid and shouldn't be allowed to one of your friends, then that's fine. I personally think that saying something like that would make you kind of an a**, but as long as you're not hurting anyone you should be allowed to say it. I feel as though critiquing certain aspects other religions or cultures, whether it be for entertainment, debate, etc, is even more justified. If the question is asking whether or not we should be allowed to discriminate against another person based on their religion or culture, though, than that's completely different. The answer would be a hard no.
Why should people have to monitor what the say in order to please everyone? We were created with free will, what I say is my business and I should hold any repercussions for it. Your religion is your choice and I should be allowed as a peer to judge you on this decision as you are not born a "muslim" or a "christian", your familt force this upon you and when you get to adulthood, you should make your decision based on fact and what you think is right.
The 1st Amendment clearly states that we have a right to freedom of speech and opinion, so we can think of religions or cultures however we want, constitutionally. That doesn't mean that it's right to judge, but it does mean we HAVE a right to judge. To not allow this would be unconstitutional.
I don't think judging people with religion or culture is not totally. Sometimes they are use for future references, for certain approach, environment or security. For example in religions were the members are not allowed to eat pork, as business man it is not a good taget market or if you'll have a bible study and you don't want to invite any muslims coz they might disagree with you in the middle of the session. Or if you are against polygamist marriage because it is contrary to morals then you should not make any relations to muslims. In india they have practices that if the husband dies the wife must go with him through self-immolation or sati by burning yourself. Some people will call it stupid because of some unproven belief and their ways of religious practice are sometime inhumane and degrading. Such radical muslim are doing now just like ISIS. You can even determine the behavior of a person through their culture and practices of religion. And if their religion is making the society or the community a better place.
You can't judge someone by what they believe. Just because you don't believe what they believe doesn't make them wrong or give you the right to judge them. If you were raised in a religion that isn't your fault you were taught that that is what is right. That was what you grew up with so it makes sense. Why judge people for what is out of there control. How they were raised is out of their control. You don't choose your parents, or how you want to be raised. You can't judge someone cause of how they think. You can silently judge them and their religion, but don't be a jerk about it. Don't say that it is unfair for you to have to watch your mouth in front of someone cause of their religion. You don't know them. You don't know how they were raised, or how they became whatever religion they came into.
They make the choice to be however they want to be most of the time and people just judging them is completely wrong. You shouldn't judge people just because they're being who they want to be or believing what they want to believe in. I have friends who are Muslim, Atheist, Christian, Catholic, and Jewish. I don't judge any of them and they don't judge each other, because if you're judging someone just because you don't like what they believe in then you should just not say anything and let them do what they want to do. It's their choice, not yours and you don't need to boss them around because in reality you're not their boss.
Judging others culture and religion is not FAIR to the ones you are judging for example they Muslims they wear scarfs over their heads and faces yet they could be very nice and how they live is another example people judge the way they look to the way they live and they presume they are rude and mean but they could be the most kind and sweet person you have ever met.