On the first page of the epilogue, Hailey refers to the Nation of Islam as a cult, not a religion. What tone does this word set?

In my perspective, I believe he found the Nation of Islam as a cult, not a religion because the way it starts it's own movement and preaches the difference between how whites are evil, but not the other color or race. Whereas in religion, they just follow their own customs and practices without saying anyone bad or good.