How do we know the gospel is effective?

In Isaiah 55:11, God assures us that His word accomplishes what He intends. This underscores the power of the gospel, which aligns with the doctrine of irresistible grace in sovereign grace theology. Romans 1:16 also affirms that the gospel is the power of God for salvation to everyone who believes, demonstrating its effectiveness not merely in theory but in practice. As God sends forth His gospel, it will result in the salvation of His chosen people, ensuring that none of His purposes are thwarted.