The main truth of Christianity is that God became a man. Islam rejects that truth, and so is a huge step backward. It is an extremely alienated religion.

A step backwards?  According to who? And in what sense?  If you are interested in Gnosticism you must be aware of the similarities between the Christ narrative and older Mithraic rituals.  Perhaps Christianity was a step backwards?

Alienated-same questions again.  The Muslim relationship with God is personal.  All actions are in the service of God: everyday lfe is suffused with the divine.  There is no real equivalent of priests, no intercession by saints; there are no icons, no depictions of the Prophet, no light-up Madonnas...

You seem to have found a personal answer, Alexander, and I respect that.  And I'm willing to admit I may be oversensitive because I work in the Muslim community.  But the fact that the West has fallen into the duallist trap of us (Christians and Jews) vs them (not) in this particular instance isn't an argument for creating an alternative, and equally incorrect, duality.