What are the roots of Islam in relation to Jesus Christ?

They consider Christ ,Virgin born but not the son of God(Go figure that one) They also don't believe he was crucified,that someone else was substituted at the last minute(Go figure that one too).They also consider the promises of Israel went to Ishmael,Abrahams other son by his slave girl Hagar(Also not true)and not Isaac as the Bible says.Mohammed came along 600 yrs after Christ.Allah was "El Allah" the Mooon God .Mohammed turned him into "GOD",if you don't believe it ,they will lift your head for you.