1 Timothy 6:16

ὁ μόνος ἔχων ἀθανασίαν : God the Father is the subject of this whole attribution; and it is the Catholic doctrine that He alone has endless existence as His essential property, (οὐσίᾳ ἀθάνατος οὐ μετουσίᾳ, Theod. Dial. iii. p. 145, quoted by Ell.). God the Son and God the Holy Spirit are co-eternal with the Father; but Their life is derived from and dependent on His. This is expressly declared by Christ of Himself, “As the Father hath life in himself, even so gave he to the Son also to have life in himself” (John 5:26). On this Westcott notes: “The Son has not life only as given, but life in Himself as being a spring of life.… The tense (gave) carries us back beyond time”. Accordingly, the creed of Cæsarea, which formed the basis of that adopted at Nicea, spoke of the Son as Ζωὴν ἐκ Ζωὴς; a doctrine sufficiently expressed in the other phrase, φῶς ἐκ φωτός, which has survived.

φῶς οἰκῶν ἀπρόσιτον : This is a grander conception than that in Psalms 104:2, “Who coverest thyself with light as with a garment”. Here, if one may venture so to express it, the Person of God is wholly concealed by His dwelling, which is light; and this dwelling is itself unapproachable. Josephus, Ant. iii. 5. 1, says that God was thought to dwell in Mount Sinai, φοβερὸν καὶ ἀπρόσιτον. (See also Philo, de Vita Mosis, ii. [iii.] 2 cited by Dean Bernard).

ὃν εἶδεν οὐδεὶς ἀνθρώπων : None of men; only the Son (John 1:18; Matthew 11:27, etc.).

κράτος : For this word in doxologies see reff.