But this is not so. Not one has gained all the ground. In fact Muslim religion is the only religion that had an absolute phenomenal rise. It was spread with the Koran in one hand and the sword in the other. Accept it or die. For six hundred years there was no stopping it and then there was a halt even to it.
God is same or Allah is the same but his children may call him differently and may worship him differently. That does not mean God loves them differently. If one child were to kill the other or hurt the other, is it possible by any stretch of imagination that God would be happy and reward him?
In realizing God, ideals and methods may differ but that is the central point. There may be a thousand different radii but they all converge to the one centre that is realization of God.
All the great religions of the world evolved in different eras to solve the problems of the people in that era. All religions have a soul. The soul may be different but the religions are supplementary to each other and not contradictory. Each religion, as it were, takes up one part of the great universal truth and explains or embodies it. So every religion is an addition and not exclusion. And this is probably how humanity has marched.
People if they respect their religion should stop comparing religion. It is too personal a thing.