Why does it matter that Mary and Joseph were Jews?

Answer 1

God in Heaven even before the foundations of the world were put in place had a plan for His creation. In this plan He knew he would have to have a Savior for the world. This Savior would come through a chosen group of people, a people who God would guide and nurture to bring blessings to the world. The group of people became the Jewish nation of Israel. The Savior was His own dear Son, Jesus Christ, The Savior when He was born a man had to have Jewish parents and so Joseph and Mary were both Jewish from the tribe of Judah, the perfect parents for the Savior who came from the Jewish nation. Parents from a Gentile nation would not do.