Islam, a Christian heresy?

John of Damascus has declared Islam a Christian heresy, since non Christian religions aren't defined this way are not Muslims a Christian offshoot? A majority of Christians accept Mormons as Christian, 51%, If we accept Mormons as Christians why not Muslims?

Little do people realize that the reasons for Muslim rejection of certain Christian dogmas is out of respect for Jesus not necessarily due to religiosity. Some examples of this are Jesus not being God's Son because Jesus is the Word and Spirit of God who prexists, in a sense God Himself. Another is Jesus didn't die on the cross, again not because of religiosity (not to doubt Christian dogmas per se) but rather because Jesus was too good to be killed by man, He is too great to be slain. Also the rejection of the Trinity seems also like they wanted to have a Unitarian approach, not uncommon even now, that Jesus as the Word and Spirit is one with God. It was argued once that "who loves Christ more, those who say He was killed and sent to hell or those who say He was saved and sent to heaven." On the surface it seems like a good argument but realizing that His physical death was all about defeating death itself thus also about defeating satan, gives us more insight nd clarity.

Just something to ponder.