Mark 16:20 And they went forth, and preached everywhere, the Lord working with them, and confirming the word with signs following. Amen.
When Jesus left the Earth He left His followers, Believers, with the commanded mission to preach the Gospel in all the world. He also declared that there would be supernatural signs following to confirm the Word. Jesus intended Believers to do the works He did and greater works with the same supernatural power of the Holy Ghost. Supernatural power was not just for Jesus to operate in but for every Believer as well as every office of ministry.
Paul, the Apostle, and a Believer is a good example of this. Paul attributed the success of the Gospel was that he preached it with signs and wonders following it especially in Rome, Corinth, and Thessalonica
Romans 15:18 For I will not dare to speak of any of those things which Christ hath not wrought by me, to make the Gentiles obedient, by word and deed,19 Through mighty signs and wonders, by the power of the Spirit of God; so that from Jerusalem, and round about unto Illyricum, I have fully preached the gospel of Christ.
1 Corinthians 2:4 And my speech and my preaching was not with enticing words of man’s wisdom, but in demonstration of the Spirit and of power: 5 That your faith should not stand in the wisdom of men, but in the power of God.
1 Corinthians 4:20 For the kingdom of God is not in word, but in power.
1 Thessalonians 1:5 For our gospel came not unto you in word only, but also in power, and in the Holy Ghost, and in much assurance; as ye know what manner of men we were among you for your sake.
Jesus utilized power to do the works He did Acts 10:38. Jesus said the same works would be done by us John 14:12. It is supernatural power which is above and beyond the natural. It is power that cannot be explained by natural laws. The baptism of the Holy Ghost is our connection to the power source and is the spiritual experience that provides access to the power Acts 1:8; 2:4.