"Therefore I glory in Christ Jesus in my service to God. I will not venture to speak of anything except what Christ has accomplished through me in leading the Gentiles to obey God by what I have said and done- by the power of signs and miracles, through the power of the Spirit. So from Jerusalem all the way around to Illyricum, I have fully proclaimed the gospel of Christ" (Romans 15:17-19)
What a marvelous thing to exclaim that everywhere you went you fully proclaimed the gospel of Christ without reservation. What a great feeling to know that your life was given for the good news of Jesus, which has the power to save ( Romans 1:16 ). This was the theme and mission of Paul's life. He boldly taught Christ, faced all opposition to the message and ran the race set before him unto a glorious finish.
What is most amazing about this declaration is that Paul would not boast in anything except what the Lord Jesus accomplished through him. His mission was to lead the Gentiles to Christ, he was the apostle set apart from birth for this specific purpose ( Romans 1:1 ). Everywhere Paul went people came to the Lord because of the word he taught and the demonstration of power that accompanied him. The Holy Spirit verified by signs and wonders that he spoke on behalf of God. Paul was the willing participant and the instrument God used to herald His amazing news to the world.
This is an important truth to understand; God confirms his Word by demonstration of power through the Holy Spirit. Jesus established this truth throughout the gospels. When people cornered him asking if he was the Messiah he would answer them like this, "I did tell you, but you do not believe. The miracles I do in my Father's name speak for me" ( John 10:25 ). He never answered them by his own testimony, because the works he did testified to who he was (see John 5:36; John 10:38; Matthew 11:4; John 2:23; Matthew 13:17 ). To answer them plainly would not have satisfied Jesus, because the works that Jesus did were the evidence and necessary credentials that he was indeed the Messiah promised and sent by God. Every miracle, sign and wonder that Jesus preformed was a fulfillment of what the prophets had foretold about the promised Messiah. They testify that he came on behalf of God.
Even in the Old Testament, the prophet of God demonstrated that he was God's spokes person by performing miracles. Consider Moses as an example; he told Pharaoh to let the children of Israel go and demonstrated his command with the plagues because of Pharaoh's hardness of heart. When Pharaoh finally let the Istraelites go, Moses parted the Red Sea, he produced water from a rock, and he led the Israelites through the desert following the pillar of fire and stood by while God fed them quail and manna for those many years. This was the proof that Moses spoke on behalf of God, because the Lord verified His word by these signs and wonders.
Elijah had similar experiences. To prove that He was the prophet of the only true God, he challenged the prophets of Baal to a battle. He drenched the alter in water and asked God to send fire down from heaven to consume the offering. Immediately fire came down and burned up everything. He also prayed that it would not rain and it didn't for over 3 years. Then when he prayed again, the heavens opened up and poured down rain upon the earth. This is the proof of the prophet, the words spoken were confirmed by miracles. There are countless others who experienced the same verification; Joshua, Samson, Elisha, Jeremiah, Jonah, just to name a few.
This is a great reminder for today. Paul experienced many people coming to the Lord by the gospel he preached and the work of the Holy Spirit present to confirm that the Word was true. We too are ministers of the good news of Christ Jesus. We should also expect confirmation by the Holy Spirit of the words we speak in preaching the good news of Christ. It is my hope that at the end I will proudly boast of what has been accomplished by Jesus living through me. I will always be ready to share the gospel with anyone who has an ear to hear and I know that Holy Spirit will confirm the word spoken, because the gospel is the power of God for the salvation of everyone who believes ( Romans 1:16 ).