In the book of Acts the apostles began to preach after Jesus' ascension the gospel of the Kingdom. This is the same gospel Jesus preached and great miracles were written with this type of preaching. One could speculate and it is obvious we are not seeing the mighty works of Jesus or the apostles today because we have deviated from preaching the gospel of the Kingdom. Today, there are all types of preaching: the gospel of grace, the gospel of prosperity, the gospel of healing but no obvious power. Acts 17:6 says these men (the apostles) have turned this world upside down.
Why, because they preached the gospel of the Kingdom. If we return to preaching and teaching the Kingdom message, we will turn this world right side up. The power will return, the anointing will return, the glory of God will return, and we will see mighty works of God happening in all nations. We will witness in this day the apostles and prophets' band together, Jews and Gentiles band together, spiritual gifts in operation like never seen before. This is the day that the army of the Lord is seen marching forth shattering the spiritual walls of religion and apostasy. God is saying to those that have ears to hear, take another look into the spirit realm, take another look into the supernatural and great and mysterious things will be revealed.