Does everyone want to know why christianity and Islam made it to the top?
Because they are both monothiestic religions. The one flaw in a polythiestic relgions is that there is more then one god, making it possible for the integration of other pantheons. To the followers of polythiestic religions, many of them would encounter the other cultures with a different set of gods and would revere them as well. This is because that there is the possibility that those gods might exist aswell, and pissing them off is a bad idea.
However, with a monothiestic religion, there is really just one god. Said god is all powerful and all knowing, in just about every case. So both the christians and muslims could, infact, ignore the gods of other pantheons completely, because they only have one absolute god. Then, the could persecute and make war against other cultures of "infidels" without having limits.
That is why monothiesm always rises to the top over polythiesm. An excellent comparison is between democracy and dictatorship. In the dictatorship, things get accomp-lished much faster because all the power derives from one "all-powerful" figure.