The expression “diamond in the rough” refers to a person who has much potential, but it has not yet been developed. Some people with great potential never develop, while others do. Apollos was one who did (Acts 18:24-28). Can we learn from him? Apollos had potential greatness (vv. 24-25). Apollos was preaching effectively. Although one does not need to be versed in eloquence to be sufﬁcient for the Lord, Apollos had the potential to be greatly used because of his talents. The trouble was that Apollos did not know the whole story or the full gospel of Christ. He only knew about the baptism of John, which was a baptism of repentance. He did not to know the full story about the Lord Jesus Christ.
Apollos had a perfected understanding (v. 26). Aquila and Priscilla took Apollos aside and corrected his erroneous views of the gospel. Apollos needed additional teaching and training for his work in the kingdom of God. Along these lines, this is what we need to do for those who have undeveloped potential — we are to train them! If someone has an inadequate understanding of truth, they need to be taught. If someone is apprehensive about their abilities to teach, preach, or participate in worship, they need to be shown how to perform these tasks. One of the best ways a congregation can grow is by training which makes the members stronger and better at what they do.
Apollos had a powerful ministry (v. 27). Apollos went on to be a great preacher for the Lord. The success of Apollos was not due to his eloquence, but was due to his preaching of the truth and his love for the Lord. This was the source of power in his preaching. If you are a “diamond in the rough,” you can be made better and more useful for the Lord. All it takes is a willing mind and good brethren who want to help you grow.