The gospel is the power of God for salvation

“For I am not ashamed of the gospel, for it is the power of God for salvation to everyone who believes, to the Jew first and also to the Greek. For in it the righteousness of God is revealed from faith for faith, as it is written, "The righteous shall live by faith.” - Romans 1:16-17

“The gospel is not advice to people, suggesting that they lift themselves. It is power. It lifts them up. Paul does not say that the gospel brings power but that it is power, and God’s power at that. When the gospel is preached, this is not simply so many words being uttered. The power of God is at work. When the gospel enters anyone’s life, it is as though the very fire of God had come upon him. There is warmth and light in his life.The power of God of which Paul writes is not aimless but directed to salvation. It issues salvation. This is the general term of which justification, redemption, and the life are particular aspects.”

- Leon Morris in his commentary on the epistle to the Romans