Matthew

Jewish People, to assure them that Jesus was the long awaited Messiah

Mark

For Gentiles, Non-Jewish people who suffered persecution to comfort them by assuring them that Jesus suffered persecution as well.

Luke

To Christians about the compassionate Jesus to assure his readers of Jesus' kindness, love, and mercy.

John

Jewish People for those who might have not known Jesus and focused on Jesus' message as one that only the Son of God could live & teach.