Apollos was a Jew from Alexandria. He is described as being eloquent and mighty in the Scriptures. However, while he was proficient in the Old Testament, he did not know about Jesus.
Acts 18:24Now a Jew named Apollos, a native of Alexandria, came to Ephesus. He was an eloquent man, competent in the Scriptures.Acts 18:25He had been instructed in the way of the Lord. And being fervent in spirit, he spoke and taught accurately the things concerning Jesus, though he knew only the baptism of John.
Therefore, while he was teaching only the baptism of John the Baptist, he learned about Jesus from Aquila and Priscilla, and based on this, he became a very excellent Bible teacher.
Acts 18:26He began to speak boldly in the synagogue, but when Priscilla and Aquila heard him, they took him aside and explained to him the way of God more accurately.Acts 18:27And when Apollos wished to cross to Achaia, the brothers encouraged him and wrote to the disciples to welcome him. When he arrived, he greatly helped those who through grace had believed,Acts 18:28for he powerfully refuted the Jews in public, demonstrating by the Scriptures that Jesus was the Christ.
However, his teaching was so outstanding that it seems many in the Corinthian church became his followers.
1 Corinthians 1:12What I mean is that each one of you says, “I follow Paul,” or “I follow Apollos,” or “I follow Cephas,” or “I follow Christ.”
1 Corinthians 3:4For when one says, “I follow Paul,” and another, “I follow Apollos,” are you not being merely human?1 Corinthians 3:5What then is Apollos? What is Paul? Servants through whom you believed, as the Lord assigned to each.1 Corinthians 3:6I planted, Apollos watered, but God gave the growth.1 Corinthians 3:7So neither he who plants nor he who waters is anything, but only God who gives the growth.1 Corinthians 3:8He who plants and he who waters are one, and each will receive his wages according to his labor.1 Corinthians 3:9For we are God's fellow workers. You are God's field, God's building.