Authority to Preach

Matthew 10:1, 5-8
1 And when He had called His twelve disciples to Him, He gave them power over unclean spirits, to cast them out, and to heal all kinds of sickness and all kinds of disease. ... 5 These twelve Jesus sent out and commanded them, saying: “Do not go into the way of the Gentiles, and do not enter a city of the Samaritans. 6 But go rather to the lost sheep of the house of Israel. 7 And as you go, preach, saying, ‘The kingdom of heaven is at hand.’ 8 Heal the sick, cleanse the lepers, raise the dead, cast out demons. Freely you have received, freely give.

The authority Jesus gave to the apostles, His 12 disciples, was to tell God's chosen people that His kingdom is come. God brought it down before us, and proof of that message was in the power over the curse to include disease and possession. But the message behind the signs was their purpose - to show the authority of Jesus and so His followers as the kingdom's ambassadors. We are His ambassadors to call men to be reconciled to God.