IMHO, the "god" proclaimed by Muslims is not the same God of the Bible. Mohammad came from a polytheistic background and decided, through "divine revelation" to pick 1 of the many gods worshiped by his brethren (Allah) and proclaim that this is the ONLY true god. This is why Mohammad was rejected by both Jews and Christians during his "peaceful" campaign in Mecca. He turned violent when he found a willing and able army in Medina which conveniently happened to coincide with his "new" revelation of domination and forced conversion through jihad.

Those who continued the ways of the Pharisees ("jews" who reject Jesus the Christ as the prophetic Messiah) also worship an entity other than the God of the Bible. That is why Jesus himself told said Pharisees that they are of their father the devil. Satan is who they follow and worship - their "God".

The rejection of Jesus of Nazareth, the Christ our LORD, is the ONLY test which denotes whether or not the True God is the One being evoked. Those who reject Him worship false god(s). Unitarianism, gnosticism, theosophy, hinduism, occultism, kabbalism, etc. ALL reject the truth of Jesus of Nazareth as LORD and Savior, therefore, they worship "other gods" which is a direct sin against the Pre-Existent One - The Creator of ALL things. Many of these belief sets claim that "God is everything and everything is God". This is a humanistic belief which was offered, and accepted, in the garden as the original lie. The belief that man can be equal to God is first lie where from ALL other lies derive.

"Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind. This is the first and great commandment. And the second is like unto it, Thou shalt love thy neighbour as thyself. On these two commandments hang all the law and the prophets."

If you do not know the TRUE Lord thy God, you cannot fulfill these two essential Commandments.