Christianity didn’t come into being for 2,000 years after Abraham, but he still believed in the Messiah and it did happen. Muslims are Ishmaelites and they still fight against the whole world and the world still fights against them. Isiah was born of freedom and Ishmael was born of slavery. Sin is slavery and belief in Jesus Christ is freedom from the slavery of sin.
Islam did not exist until about 700 years after Christ. The people who descended for Ishmael did exist, but they were tribal nomadics, fighting with each other, and practiced no organized unifying religion. Ishmael and Islam are not the same thing even though some of the people in the religion may be related to Abraham and Hagar (as all Semitic people are). To make Judaism and Islam a kind of opposite equal is not correct. If anything, Islam attempts to subvert all the existing religions in the area to unite those people in war against what they see as their oppressers.