Fighting for supremacy

The evolution on this planet has the same rules for every living being:
It is s struggle for survival!
The consequence is that everybody is fighting against all others.
Of course, some discover that building a group can help to survive. But then groups also compete against each others. A group can be just a family, or an ethnic population, or a nation or a coalition of nations.
But also a religion!! A religion, seen as a group of people who believe to the same faith, also try to survive and fight against all other religions.
In this sense religions build walls between people. I see it as a medioeval castle, with an "inside" and an "outside". Inside the good people which should be defended from the bad people which are outside.
In every religion we have different branches, and usually they are not very nice to each other.
I may also say that religions have been a bad thing for humanity, and they are still today, with some major progress in some religion and some backward-thinking in some other.