How do we know the mystery of salvation is true?

The mystery of salvation, which is not comprehensible by natural understanding, is revealed to believers through the Holy Spirit. As seen in 1 Corinthians 2:10-12, the Spirit searches and reveals the deep truths of God to us. This truth is often hidden from the wise and learned but is disclosed to those who approach God with humility and faith, as indicated in Luke 10:21-22. Hence, our confidence in the truth of salvation lies not in human reasoning but in divine revelation, confirming the validity of the gospel as the means through which God's grace is imparted to His people.