'That' is used when you must have it to identify what you are talking about. "The boy that fell is not injured." - In this case we need to know which boy it was. 'Which' is used to add some information, but does not necessarily serve to identify what we are talking about. 'Tom's house, which was built in the 1800's, is still in good shape." - We know which house it is. It is Tom's house, so the house is identified. The phrase in the middle just adds information - in this case, when it was built. Sorry, forgot the correct answer: "But there is a part of our behavior that is not determined by religions that are present in society. " Both phrased are used to uniquely identify first the behavior and then the religions. In normal spoken English, few people would notice the difference.

Vassili, Well, you can see that there is a difference of opinion even among experts. There are rules and then there is usage. In actual usage writers employ which or that interchangeably in a sentence like yours, whether the writing is formal or informal. My opinion: You can use which or that in your sentence. It is a question of style. There is no difference in meaning. -that or which to introduce a restrictive clause (without a comma) -which to introduce a nonrestrictive clause ( after a comma...,which)

It doesn't matter which word you use in this context. Which is "more" correct, but both are fine. Explanation here: http://public.wsu.edu/~brians/errors/which.html

"There is a part of our behavior that is not determined by religions which is still exist in our society. "