25. This man was instructed in the way of the Lord . . . knowing only the baptism of John--He was instructed, probably, by some disciple of the Baptist, in the whole circle of John's teaching concerning Jesus, but no more: he had yet to learn the new light which the outpouring of the Spirit at Pentecost had thrown upon the Redeemer's death and resurrection; as appears from Ac 19:2, 3.
      being fervent in the spirit--His heart warm, and conscious, probably, of his gifts and attainments, he burned to impart to others the truth he had himself received.
      he spake and taught diligently--rather, "accurately" (it is the same word as is rendered "perfectly" in Ac 18:26).

JFB.