How do we know the mystery of the gospel is true?

The mystery of the gospel, as Paul describes it in Romans 16:25-26, was kept secret since the world began but has now been made manifest through the Scriptures of the prophets. The revelation of this mystery signifies God's plan for salvation, which includes all nations, as foretold by the prophets. This revelation was not random; it unfolded in God's perfect timing, demonstrating His sovereignty and the truth of His word. The historical fulfillment of God's promises through Christ serves as a robust confirmation of the gospel's truth.