The concept of monotheism is not only a basic teaching of the Prophet Muhammad but is also enshrined as an established reality, even in the interpolated versions of the Torah and the Bible. Judged on this established criterion, Islam, unlike Judaism and Christianity, is proved to be a perfectly true religion. Monotheism implies belief in only one God. He alone should be worshipped. No one should be associated with Him. No man should be accorded that special place which is the sole prerogative of the Lord of the Universe. This concept of monotheism is preserved in its pure form only in Islam in the Quran. Other religions, while accepting monotheism ideologically, also adopted almost everything that ran counter to it. While believing in God as the Sustainer, in practice they accorded that status to their saints.