Every person has a God. Their God is whatever they have the deepest belief in, the most faith in, and draw the most strength from. People may object to someone else's God if they instinctively feel it is a threat to their own God. Accordingly, if their own God is their ego (which it very often is), then you can easily predict what their response may be to a God that apparently lies outside the boundaries of their ego.

And the greater their level of hostility, the greater is their fear.

An egotistical practice of an organized religion is to insist that it is the one, the best, and the only true religion, and to look down on all other organized religions.

An egotistical practice of atheism is to do the same from that point of view. Atheism is itself a faith-based religion, one that takes pride in not being "religious". :-)