How do we know the sovereign grace gospel is true?

Paul states in Galatians 1 that the gospel he preaches is not of human origin but has been revealed by Jesus Christ. This assertion is crucial because it establishes the gospel as a divine truth rather than a human fabrication. The gospel is grounded in the sovereignty of God, emphasizing that salvation is not initiated by man's choices but is entirely dependent on God's grace and purpose. Furthermore, the promises within the gospel are assured and immutable, supported by references throughout Scripture that affirm God's sovereignty over all things, including salvation.