I agree all the world's organised religions derive from a common source but the Bible is different. Unlike other belief sytems, it does not derive its teachings from the source that the established religions have been manufacured out of.
I respect you have a different opinion but I believe you are mistaken.
The reason why the Christian establishment is slow in reconciling Christianity with other faiths and we know this is the case because the head of the Church of England has accepted an honourary membership of a Druidic Order and the Pope is covertly advocating the philosophy of the UN, is because too many of its followers still adhere to the teachings of the Bible, which strictly counsels against mixing with pagan religions.
What should unite people together, should be the love for peace. It isn't necessary that we should all have the same belief in this life. We can still have different beliefs and still be able to get along, as many people already do that have different beliefs.