And when he desired to cross to Achaia, the brethren wrote, exhorting the disciples to receive him; and when he arrived, he greatly helped those who had believed through grace; for he vigorously refuted the Jews publicly, showing from the Scriptures that Jesus is the Christ. Acts 18:27-28

Apollos had likely been preaching a “gospel“ of repentance, without Christ and the whole gospel. After Aquila and Priscilla helped Apollos to understand the gospel correctly, he wanted to go to Corinth (see Acts 19:1).

The leadership at Ephesus (including Aquila and Priscilla, presumably) sent Apollos on his way with letters of affirmation and recommendation. This is important, even today, as there are so many false teachers looking for a pulpit. We should be discriminating about who we accept as teachers, and legitimate teachers will not be offended by such inquiries.

When Apollos arrived in Corinth, God blessed and used him as both a teacher of good doctrine and a voice of warning regarding bad doctrine. Good teachers must be prepared and willing to do both today as well. Why? Again, because there are so many false and dangerous teachers spewing so much false (and incomplete) doctrine. God’s people need both to hear the truth and be warned of falsehood.

A last thought: Those who speak false doctrine are dangerous. But even more dangerous are those who do not speak false doctrine, but who are guilty of not speaking the whole truth. These false teachers either spew “empty feel-good platitudes,” or a message of “religion and works.” What they fail to do is proclaim Christ and the gospel! The Church must demand that teachers (a) preach the Word of God, and (b) Christ and the gospel!