The HOLY QUR'AN EVEN STATES THAT WE ARE NOT ALL SUPPOSED TO WORSHIP THE SAME WAY. This is stated in Sura 22/67“ To every People have We appointed rites and ceremonies which they must follow: let them not then dispute with thee on the matter, but do thou invite (them) to thy Lord: for you are assuredly on the Right Way.” Sura 22/67
The idea that it states that Muslims can invite others TO THEIR LORD is a recognition by them that there are other Lords and that rites and ceremonies have already been appointed to other peoples that they MUST follow.
In light of this recognition since we are the oldest on the planet...why haven't we reached back in history to find out what the rites and ceremonies of our people were which existed before any of this other man made stuff that basically borrowed and stole from our ancestors to create what they now have?
And for those who follow Islam; Prophet Muhammad prophesied that "there would be more sects in Islam than there are in Christianity"...although the whole story is another issue altogether and is one that is best understood from a historical and political level as well as a power level.