That the Lord from eternity is Jehovah, is known from the Word; for He said to the Jews: “Verily, verily, I say unto you, Before Abraham was, I am” (John 8:58); and elsewhere, “Now, O Father, glorify thou me. . . with the glory which I had with thee before the world was” (John 17:5). And here the Lord from eternity is meant, and not a Son from eternity; for the Son is his Human conceived of Jehovah the Father, and born of the virgin Mary in time, as was shown above:
That the Lord from eternity is Jehovah Himself, is evident from many passages in the Word, of which only these few will be adduced at present: “It shall be said in that day, This is our God; we have waited for Him, that He may save us; this is Jehovah, we have waited for Him; let us be glad, and rejoice in his salvation” (Isaiah 25:9); from which it is manifest that God Jehovah Himself was expected.
“The voice of one crying in the wilderness, Prepare ye a way for Jehovah, make straight in the desert a highway for our God. . . The glory of Jehovah shall be revealed, and all flesh shall see it together. . . Behold, the Lord Jehovah cometh in strength” (Isaiah 40:3, 5, 10; Matthew 3:3; Mark 1:3; Luke 3:4); here also the Lord who was to come is called “Jehovah.” “I Jehovah, . . . will give Thee for a covenant of the people, for a light of the nations. . . I am Jehovah, this is my name; and my glory will I not give to another” (Isaiah 42:6, 8).
The Lord is “a covenant to the people, and a light of the nations,” as to the Human. Because this is from Jehovah and was made one with Jehovah, it is said, “I am Jehovah, this is my name; and my glory will I not give to another,” that is, not to any other than Himself: “to give glory” is to glory or to unite to Himself. . .
From the passages which will be adduced below, it will be manifest that by “the Lord” and also by “Jehovah,” after his Human was glorified, is meant the Divine and the Human together as one; and that by “the Son” alone is meant the Divine Human.
from The Human Made Divine, Pages 129-130