Atheism and Anti-Theism same thing?

[God of Mr. Hanky]

I cannot understand how an institution like religion can cause so much harm to society when its core belief is to help.

That is not the core belief of any religion. If it was, then it would be the core belief of all religious organizations which have influenced the societies of nations, and there would be far less conflict between them. For what that would be worth, there may be no religious differences at all.

The problem with religious institutions is that they are institutions first, where job security of the leadership always comes first. Therefore they bring people in through manipulative differentiation between them and the "others". They teach their followers that the good which is in them naturally depends not on who they are by nature, but on what they believe and practice. Ultimately, the believers are led to believe that only the help which they bring to society is really any good, while those "others" who do charity and other good deeds necessarily have some ulterior motive (like that even matters).

Teaching people that they can be helpful in society only if they believe follow a specific religion = something not very helpful at all.