In Jesus' day, people were used to authority; it was everywhere.  The occupying Roman forces had the right to make people obey Roman law; but the soldiers would exceed their authority, demanding bribes under threat of false arrest (Luke 3:14).  Religious leaders forced people to keep the Law of Moses and many extra rabbinical traditions, but they had no place for Jesus (Luke 11:52): and it was the religious 'temple guard' who arrested Jesus (Luke 22:52).  Later, Saul, (who became Paul the Apostle after his conversion) had authority from the chief priests to arrest Christians and throw them into prison (Acts 22:4-5).

But Jesus came with a different authority (John 10:17-18).  Instead of oppression, Jesus brought freedom; instead of imprisonment, freedom.  His words brought God's law to life and whenever He spoke, people listened - because they knew He was speaking to them (Luke 4:16-22).  But the greatest amazement came when He commanded evil spirits to leave the individuals they had been dominating (Luke 11:20). The demons listened and were compelled to obey.  In the previous verses, a demon used the mouth of the man he controlled to ridicule Jesus; but at Christ's command the demon had to come out of the man.  Angry at being dismissed, Satan's agent made the man collapse.  But the man was unharmed.  When he got up, he was totally free from demonic oppression (Luke 4:33-35).

People who do not believe that Jesus Christ has authority over Satan and his demons, make a great mistake.  Those who think that the main work of the church is in changing society by doing good have missed the point.  The reason Jesus came was to destroy all the work of the Evil One (1 John 3:8) so that we can be set free to receive God's grace and worship Him with released hearts.  Only Jesus has the authority to tell Satan what to do and where to go: and only those who trust the Saviour have authority to use His Name against evil (Acts 19:13-20).

Until Satan is finally eliminated, he is our greatest foe: in comparison, all the people who trouble us have no power (Ephesians 6:12).  They are not the enemy, Satan is.  But Jesus is the friend of every sinner who turns to Him (see www.crosscheck.org.uk to know more), because Jesus still has real authority over all the powers of darkness.  Until He returns, those who trust in Him are protected by the power of His Name (John 17:11).  So, when we are spiritually oppressed or attacked, we should not fear but claim the protection of Jesus.  When we see evil around us, do not fight the people (they don't understand how they are being used), let the power of the Name of Jesus deal with the Evil One.