Immanuel, God with Us

While the Christmas story often focuses on the baby Jesus lying in a manger, that scene was only the start of His mission.  Jesus, also called Immanuel, which means "God with us," was the manifestation of God Himself in the form of a human, first appearing as a baby in a humble manger.  But why did God do this?  Why did He come to earth as a human in the first place?  And what proof do we have that He was indeed God in flesh?  This teaching addresses those questions.