He did not know about Christ he only knew of God in scripture Acts 18:24 "And a certain Jew named Apollos, born at Alexandria, and eloquent man, and mighty in the scriptures, came to Ephesus."Apollos was a well learned and educated man. Apollos knew the Scriptures from Genesis to Malachi, completely. Acts 18:25 "This man was instructed in the way of the Lord; and being fervent in the spirit, he spake and taught diligently the things of the Lord, knowing only the baptism of John."Apollos was an preacher and teacher in the Word, and he was strong in the Spirit, and had much faith in the Lord. This is about twenty years after Christ's ascention into heaven, yet this man from Egypt had never heard of the baptism of Christ and of the Holy Spirit. Apollos had heard of the baptism of John, and that was the baptism that he taught. This lets us know that the Word did not travel as it would later. Acts 18:26 "And he began to speak boldly in the synagogue: whom when Aquila and Priscilla had heard, they took him unto them, and expounded unto him the way of God more perfectly."This man was experienced in the Scriptures, only it took Priscilla and Aquila to bring him up to date on the matters concerning Christ. It became obvious when they heard Apollos that he had not heard of Christ, so they trained him in the word. Apollos knew that the Messiah was promised in the Scriptures, and now he knows that the Messiah has come, and the Scriptures are fulfilled.