Islam traces it's heritage back to Ishmael, the bastard son of Abraham and Hagar:
Judaism and Christianity both trace their roots back to Isaac, I'm sure I don't need to post scripture to verify that.Gen. 16:1
Now Sarai, Abram's wife, had borne him no children. But she had an Egyptian maidservant named Hagar; 2 so she said to Abram, "The LORD had kept me from having children. Go sleep with my maidservant; perhaps I can build a family through her."
16:4 He slept with Hagar, and she concieved.
16:10 The angel added, "I will so increase your descendants that they will be too numerous to count." 11 The angel of the LORD also said to her; "You are now with child and you will have a son. You shall name him Ishmael, for the LORD has heard your misery..."
The big differences of course are:
1. Christ's divinity
2. Shahadah "...and Mohammed as his prophet"
The Muslim's recognize Christ as a prophet of God, the same way they recognize Moses. Therefore the Muslim's don't discount Christ's existence, they just believe that Christians have it wrong in relation to his divinity.
Christians don't recognize Mohammed as a prophet at all, I think most probably believe he was a madman, with hallucinations brought on by living in the desert. Christians have the trinity, but they are all parts of the same. ONE. If the trinity was worshipped individually wouldn't Christianity be another polytheistic religion?
These two 'facts' to me, do not negate that the God of these three major religions are one and the same... Let me know.
