What does Luke 6:17 mean?
Luke's account of Jesus' ministry before the crucifixion is thematic, not strictly chronological. First, he presents several occasions that differentiated Jesus' followers from the Pharisees and scribes who are planning to destroy Him. Then Jesus chooses twelve lead disciples (Luke 5:1—6:16). Now, Luke records Jesus' ministry to and teaching of the larger group of disciples.The audience is made of three groups. "Them" are the twelve apostles. The "disciples" are the larger group that follow Jesus; more than just the Twelve travel with Him and consider Him their teacher (Acts 1:21) although not all of them stay with Him (John 6:66). The "great multitude" are most likely there to find physical healing and freedom from demons. Luke points out that Jesus' popularity has spread.
The Greek for "level place" is translated literally, but it can mean a mountain plateau, so this could be Luke's synopsis of Matthew's Sermon on the Mount (Matthew 5—7). Even so, it's highly likely that Jesus taught the same truths on multiple occasions.
It's interesting to note that Jesus' teaching is aimed at His crowd of disciples, but the multitude—including Gentiles from Tyre and Sidon—is welcome to learn and listen, as well. In fact, Jesus finishes His presentation of what it looks like to be His disciple with an invitation to make Him the basis of their lives (Luke 6:46–49). Discipleship is more than receiving healing and passively listening to stories. It's about founding one's life on Jesus, and all are welcome to do so.
Judea is the primary district of the Jews and surrounds Jerusalem from the Jordan River to the Mediterranean Sea. It appears that sometimes Luke uses the term to mean any place where Jews have a significant population, like Galilee. Tyre and Sidon are north of Galilee, on the coast of the Mediterranean. Jesus visits Tyre and Sidon where He heals a Syrophoenician woman's demon-possessed daughter (Mark 7:24–30).