This man was instructed - Greek: was catechised. He was instructed, in some degree, into the knowledge of the Christian religion. By whom this was done we have no information.
In the way of the Lord - The word “way” often refers to doctrine, Matthew 21:32. It means here that he had been correctly taught in regard to the Messiah, yet his knowledge was imperfect, Acts 18:26. The amount of his knowledge seems to have been:
(1) He had correct views of the Messiah to come - views which he had derived from the study of the Old Testament. He was expecting a Saviour that would be humble, obscure, and a sacrifice, in opposition to the prevailing notions of the Jews.
(2) He had heard of John; had embraced his doctrine; and probably had been baptized with reference to him that was to come. Compare Matthew 3:2; Acts 19:4. But it is clear that he had not heard that Jesus was the Messiah. With his correct views in regard to the coming of the Messiah he was endeavoring to instruct and reform his countrymen. He was just in the state of mind to welcome the announcement that the Messiah had come, and to embrace Jesus of Nazareth as the hope of the nation.
Being fervent in the spirit - Being zealous and ardent. See the notes on Romans 12:11.
Taught diligently - Defended with zeal and earnestness his views of the Messiah.
The things of the Lord - The doctrines pertaining to the Messiah as far as he understood them.
Knowing only the baptism of John - Whether he had himself heard John, and been baptized by him. has been made a question which cannot now be decided. It is not necessary, however, to suppose this, as it seems that the knowledge of John’s preaching and baptism had been propagated extensively in other nations beside Judea, Acts 19:1-3. The Messiah was expected about that time. The foreign Jews would be waiting for him; and the news of John’s ministry, doctrine, and success would be rapidly propagated from synagogue to synagogue in the surrounding nations. John preached repentance, and baptized with reference to him that was to come after him Acts 19:4, and this doctrine Apollos seems to have embraced.