The Problem of Religious Diversity was first stated back in the 18th Century, when the great English philosopher David Hume noted that the contrary claims of competing religions are mutually exclusive, and thus cannot all be true. Since there are a multitude of competing religions, and a multitude of equally credible yet contrary testimonies and scriptures, the probability that any given religion is true (and thus that any religion at all is true) is extraordinarily low. Consequently, it is highly probable that all religions are false.
The best explanation for the fact that different religions believe different things about God and the universe is that religion and God are human constructs that do not correspond to any metaphysical reality. It seems that religions are by no means eternal, and there are many examples of obsolete religions, such as the once powerful Greek, Roman and Norse polytheistic religions. This variability of religious affiliations suggest that the origins of religion lie in human beings and human societies, and not in the intervention of some divine being or cosmic truth. Some see religion as merely an early phase in the development of a culture or society, noting that it is often replaced with more rational or reasonable belief systems, such as science and philosophy.
Neither does it help to suggest that all religions are just different paths to the same truth: there are just too many contradictions between different religions, and the list of what all the major religions actually agree on is very short indeed. In fact, perhaps the only thing they all agree on is that everyone should have a religion and that their religion is the true one.
Anyway have a great Sunday.