What does Matthew 10:20 mean?

Jesus is authorizing His core group of twelve disciples to be apostles (Matthew 10:5–6); the Greek term literally means "sent ones." They will carry His message to the people of Israel and, later, far beyond Israel (Acts 1:8). He has guaranteed them that this will be difficult, describing a time of persecution. They cannot yet know that this season will come after Jesus' death, resurrection, and return to heaven. During this persecution, these twelve men can count on being dragged before every level of authority, including the courts of the Jewish religious leaders, secular Jewish leaders, and Gentile leaders. Some will speak before governors and kings, even, because they represent Jesus (Matthew 10:17–19; Acts 26:1–3).

These arrests and trials will not be a sign of the failure of their mission. Instead, Jesus has said this is the way God will use them to "bear witness" to high-ranking people. This is part of God's plan to carry the gospel to every level of society. Jesus insists that His disciples should not be anxious about what they will say when these moments to speak arrive. Now He says why.

When the moment comes, it will not be the apostles speaking. It will the Holy Spirit speaking through them. Jesus calls Him the "Spirit of your Father," which is a beautiful picture that God the Father will be with them, connected to them, and speaking through them through the Holy Spirit. The disciples cannot yet in this moment likely imagine the great power that will become available to them in Christ through the Holy Spirit after Jesus leaves the earth (Acts 1:8; Acts 2).