The multitudes were amazed at Jesus' preaching, because they saw a difference between the way He taught and the way the Pharisees had taught them for so many years. The Pharisees had a lot of knowledge. Jesus had even more knowledge than they had. But it was His authority that impressed His hearers, not His knowledge (Matt.7:29). If we have knowledge but no spiritual authority in our ministry, we will be like the Pharisees. God backed up the words that Jesus spoke. This is what it means to speak with spiritual authority.
Jesus told His disciples in John 15:26,27 that the Holy Spirit would bear witness along with them. This meant that whenever they preached, the Holy Spirit would back up what they said. That's certainly how I want my ministry to be at all times. As I bear witness to Jesus, the Holy Spirit must also bear witness to what I say. He must speak to the hearts of my listeners saying, "Listen to that. That's from God". Then I'll be speaking with Divine authority. But if I merely give a very accurate testimony about Jesus, and the Holy Spirit doesn't back up what I say, I won't be called a heretic, because my doctrines are all evangelical. But I will still be ministering death, and not life.
One of the greatest needs in the church today is for a demonstration of spiritual authority in the ministry of its leaders. Spiritual authority is very different from religious authority. What we commonly see in Christendom today is religious authority, where strong leaders dominate their flock.
It's easy, when we preach God's word to have power over people. People appreciate our ministry because it helps them. Then it becomes easy for us to become like little gods to our admirers. We must always live in fear of that. We must never take advantage of the authority we have over others through our gift. We must never try to run other people's lives. If we find them clinging to us, we must gently cast them on the Lord - for their own good and their spiritual growth. Our calling is to build the Body of Christ and not our own little empires. This is the way of spiritual authority.
Paul had such spiritual authority given him by God that he could even deliver a person in the church at Corinth to Satan for the destruction of his flesh so that the man could be saved (1 Cor.5:5). The man was saved later and came back to the church in repentance. Paul was the founding father of that church and such fathers have a spiritual authority that no-one else can exercise. Those apostles had Divine authority given them by the Lord to build people up. This is the type of loving authority that we need too. We see many manifestations of such spiritual authority in the life of the apostle Paul, that are a tremendous challenge to us.
When the disciples observed Jesus for 3½ years, they saw that He was totally different from the leaders and preachers they had seen in their synagogues. They had never met anyone who lived like Him or who spoke like Him. He had authority in His life and in His ministry. Until they met Jesus, they had thought that spiritual ministry was what they had seen in their priests and their bishops in the synagogues. And if they had never met Jesus, they would have made those priests and bishops their role-models. But now they had a new role Model they could follow. What our young people need are better role-models to follow. It is our responsibility to be those role-models, as men with spiritual authority.