Belief in an all powerful being who created everything, watches and judges your every action, is a world defining point of view. It is not on the same level as any other opinion you can have. By definition, each other that believes in a different god, or does not believe, lives in a different world and is sadly wrong. Differing political opinions is nothing compared to different views on the fabric of reality.
This pitches you, and your co-believers, against the rest of humanity. You are right and will be rewarded for ever. They are wrong and might burn in hell for all eternity.
This is the most fundamental separation between « us » and « them » that can be imagined.It is not a difference of culture, of social economic level, even of values or actions. You do not consider the other as different but comparable, such as nationals versus foreigners. It is the ultimate rejection of the rest of humanity.