A Good Question: How can the church in Corinth know which teachers/preachers of the gospel can be trusted? 

The Wrong (& Worldly) Method: Trust in those who are wealthy and eloquent

• But what does that say about the crucified and rejected Jesus? (1 Cor. 1.26-29)
• Wealth and eloquence alone do not prove anyone trustworth (or untrustworthy). 

A Better Solution: Letters of recommendation (3.1)

• Paul himself has written letters of recommendation (e.g. Pp. 2.19-24)
• BUT…Corinth should not need one from Paul, they are Paul’s letters! (3.1-2)
• God’s work in and through Paul proves he can be trusted (3.4-6). 

Application: How can we tell whom to trust today?

• Consult with other believers you trust and respect (1-2)
• Look for evidence of God’s work in and through that person (3-6)
• Judge what they say against scripture (OT & NT).