He began to speak out fearlessly in the synagogue, but when Priscilla and Aquila heard him, they took him aside and explained the way of God to him more accurately.
[Acts 18:26 NET]
We should know the whole gospel if we would do Christian work well.
Apollos was a Christian, and was earnest and eloquent, but he had gone in his knowledge of Christ only as far as the Baptist’s teaching. Priscilla and Aquila heard him preach, and saw the defect.
They saw that he did not know of Christ’s death and resurrection. When they had taught him the whole gospel, he became a powerful preacher.
About the best service we can do to most people we meet is to encourage them. More than half the men and women we meet any day need encouragement. One of the worst sins we can commit against others is to be a discourager.
Perhaps the trouble with a good many Christians is the same that ailed the dozen men whom Paul found at Ephesus. They had not even heard that the Spirit was given. We can have power in witnessing for Christ only when we are filled with the Spirit.