How do we know the gospel preached by Paul is true?

The authenticity of the gospel preached by Paul is grounded in its revelation from Jesus Christ rather than human reasoning or tradition. As stated in Galatians 1:11-12, Paul asserts that his message was not received from man, but through a direct revelation from Christ. This divine origin ensures that the message Paul preached holds authority and validity. Furthermore, Paul's rigorous defense against false teachings highlights the necessity of adhering to this gospel, confirming its truth and effectiveness for salvation.