Φωτίζομαι, is “to give light or knowledge by teaching;” — the same with הוֹרֶה, which, therefore, is so translated ofttimes by the Greeks; as by Aquila, Exo 4:12; Psa 119:33; Pro 4:4; Isa 27:11, as Drusius observes. And it is so by the LXX., Jdg 13:8; 2Ki 12:2; 2Ki 17:27. Our apostle useth it for “to make manifest;” that is, “bring to light,” 1Co 4:5, 2Ti 1:10. And the meaning of it, Joh 1:9, where we render it “lighteth,” is to teach. And φωτισμός is “knowledge upon instruction:” 2Co 4:4, Εἰς τὸ μὴ αὐγάσαι αὐτοῖς τὸν φωτισμὸν τοῦ εὐαγγελίου, — “That the light of the gospel should not shine into them;” that is, the knowledge of it. So 2Co 4:6, Πρὸς φωτισμὸν τῆς γνώσεως, — “The light of the knowledge.” Wherefore to be “enlightened,” in this place, is to be instructed in the doctrine of the gospel, so as to have a spiritual apprehension thereof.[2]
The true believer is enlightened, but he is enlightened in a much deeper way through the indwelling of the Holy Spirit, than the apostate through the outward teaching of God’s word and truth and the ministry of the Spirit. The enlightening of the believer leads to a changed life according to the truth with which he is enlightened. These apostates likewise had some kind of repentance and change of life obviously, having once lived with the people of God, they were not wild sinners and Christ rejecters as they became after their apostasy. Therefore, this enlightening, which is the knowledge they received through teaching did have some effect on them, but it did not have a lasting effect on them because it was not joined by faith neither was this knowledge worked into the believer’s life through the Holy Spirit. These apostates had merely natural knowledge of the things of God as they heard them within the congregation and not true and spiritual knowledge of them. John Owen observes that
“There is a knowledge of spiritual things that is purely natural and disciplinary, attainable and attained without any especial aid or assistance of the Holy Ghost. As this is evident in common experience, so especially among such as, casting themselves on the study of spiritual things, are yet utter strangers unto all spiritual gifts. Some knowledge of the Scripture, and the things contained in it, is attainable at the same rate of pains and study with that of any other art or science.”[2]
Some in the early church have connected this enlightening with baptism, which was called “illumination”, but I believe that this has little to do with the present passage as the Author does not make this connection and the use of “illumination” to refer to baptism came later in history.[3]
Concerning the word “once” Wayne Grudem says:
Similarly, the word once that is used to speak of those who “have...