Abraham's Sons and Christianity

Some people believe, and are teaching, that there is a significant role for the son of Abraham, Ishmael. They say that God blessed Ishmael in a similar way as Isaac. In doing so, they believe that this blessing allows for a religion outside of Christianity to be a valid one and that there is another path to the Father and heaven. However, is this true? What does the blessing pronounced on Ishmael have to do with the Messiah, Jesus Christ? What are the roles of the descendants of Abraham's sons in the New Testament era? Find out in this video lecture.