I alone compassed the circuit of heaven, and walked in the bottom of the deep.
Read Chapter 24
Augustine of Hippo
The apostle Paul was not only referring to the Father when he said, "Who alone has immortality." He was referring to the one and only God, which is the Trinity itself. For that which is itself eternal life is not mortal according to any changeableness. Therefore the Son of God, because "he is eternal life," is also himself understood with the Father, where it is said, "Who only has immortality." For we, too, are made partakers of this eternal life and become, in our own measure, immortal. But the eternal life itself, of which we are made partakers, is one thing; we ourselves, who, by partaking of it, shall live eternally, are another. For if he had said, "Whom in his own time the Father will show, who is the blessed and only potentate, the King of kings and Lord of lords; who only has immortality," not even then would it be necessarily understood that the Son is excluded. For neither has the Son separated the Father from himself, because he himself, speaking elsewhere with the voice of wisdom (for he himself is the Wisdom of God), says, "I alone compassed the circuit of heaven." And therefore it is even more unnecessary that the words "who has immortality" should be understood of the Father alone, omitting the Son, when they are said thus: "That you keep this commandment without spot, unrebukeable, until the appearing of our Lord Jesus Christ: whom in his own time he will show, who is the blessed and only potentate, the King of kings and Lord of lords; who only has immortality, dwelling in the light that no one can approach; whom no one has seen or can see: to whom be honor and power everlasting. Amen." In these words neither the Father, nor the Son nor the Holy Spirit is specially named, but the blessed and only potentate, the King of kings and Lord of lords; in other words, the one and only and true God, the Trinity itself. - "On the Trinity 1.6.10"