How do we know that true preachers of the gospel exist?

In his second letter to the Corinthians, Paul contrasts true preachers with false prophets, stating, 'we are not as many which corrupt the Word of God.' True preachers declare the full counsel of God, including doctrines such as election and predestination, without shame or alteration. This commitment to integrity in preaching demonstrates their calling and authenticity. Their focus is sincere and aimed at glorifying God, and they are driven by a desire to see souls saved, rather than seeking personal gain or recognition.