Greetings in that Divine and Most Precious Name of Our Lord and Savior Jesus Christ!
God or God(s) or G-d or god or non-existent god(s) all this discussion is rather silly isn't it?
We know that simply stated, there is only ONE GOD. So whenever folks rely on the Grace of the Divine, even if it just to merely exist breathing in the vitality of the Giver of Life, surely it is God. It is not Satan or the demons or non-existent god(s) which give life, which sustain Creation, which brings about each rising Dawn. We in Rastafari say "birds in the treetops" to imply that even simple things like the birds singing their morning bird songs are part of the intricacies of God's workings, or as the Elders have said, "Even if there is just a bird in the treetops, it is God Almighty to put that bird flying up in there." Whether or not the bird is cognizant of this fact is irrelevant to the workings of God which are impartial to recognition.
We call this Synergy in the Church right? God cooperates with His Creation, and all of Creation is a reaction to God, even if we or they don't realize it. Faith is to learn to understand who God is. The Church is the depth of this relationship, where one comes to understand who God is and that Sin is what naturally separates humanity from God, and reconciliation is only achievable in the Church, through Grace and the synergy of Repentance. However, God is not somehow limited to the Church. Jews, Muslims, Buddhists, even Atheists surely all live in the realm of God, with the one and same Kingdom of God ever at hand. Now let me be very clear, ONLY IN THE CHURCH CAN WE ACHIEVE SALVATION, however this should not negate the reality that folks outside the Church have experience, and yes, even a relationship with God. There are surely enough CONVERTS on this forum to vouch this to be true, or were converts having absolutely no connection or relationship with God possible until Baptism? If not, what brought us into the Church in the first place?
That being said, I think the analysis of Muslims as being simply another Christian heresy and rightful anachronism from the 7Th century Christological debates is fairly accurate. Even Joseph Campbell makes this same assertion, concluding that the Muslim cry of "God is One" was a reaction to all the Oriental and Byzantine Christological debates. This makes sense. Further, Islam evolved in the crucible of competing Arab yet Jewish monarchies and kingdoms in Yemen and the Arabian peninsula, so further it is debatable to suggest that Muslims worship the God the Jews, which is what they themselves claim as worshiping the God of Abraham and Moses, and yes, Jesus too.
Are Muslims sometimes energized by Satan? Yes, of course. However so are we Christians, whenever we yield to temptation and Sin. When we sin we are not worshiping the Devil, and neither are Muslims when they are like ourselves energized from Satan. The catch, is can they also be energized by God? I would say yes, as can and is all life which has the Breath of Life given by God. The very fact that any Muslim is alive and breathing is a testimony of the mercy of God. We should then pray that they learn in time to come to God in repentance just as we all need to do continually.
So we should readjust our assumptions. It is not that Muslims worship the Devil, rather they simply do not worship God in the current lawful manner according to the New Covenant of the Church. ALL the world must inevitably come to the Church, Muslims included, the question we inside the Church need to ask is will be ready and receptive when God brings them to us?