How do we know if a preacher is of God?

In 1 Corinthians 12:3, Paul provides the key to discerning true from false prophets: no one speaking by the Spirit of God can call Jesus accursed, and no one can truly proclaim Jesus as Lord except by the Holy Spirit. This assertion emphasizes that authentic preaching aligns with the gospel of grace. If a preacher promotes salvation through human works rather than by grace through faith in Christ, they contradict the scriptural testimony and demonstrate themselves to be impostors. Therefore, careful discernment based on their message is critical.