I, I [1] am Jehovah. Here the Lord employs lofty language, as having obtained the victory. Already he had sufficiently explained in what manner he must be known, and had shewn that there is no God except himself; and now, in order to confirm this doctrine, he exclaims, "I alone am Jehovah, there is none besides me." This shews how dangerous it is to contrive anything about God out of our own fancy; for when we make any kind of graven image, we produce an idol instead of God. We ought, therefore, to embrace nothing but what has proceeded from God, so as not to allow ourselves any liberty on this subject. After God has revealed himself to us, we ought to make progress in the knowledge of him, and to grow and be strengthened every day; for this is the meaning of the repetition, I, I. [2] And there is no Savior besides me. That we may not suppose that his eternal essence only is here exhibited, but also his power and goodness, which he constantly exercises towards us, and by which he is fully revealed, he adds an epithet as a distinguishing mark, that "he is the only Savior." The world falls into the mistake of giving a naked and empty name to God, and at the same time conveying his authority to another, as in Popery God is indeed mentioned, but is robbed of his honor, when one part of it is given to St. Peter, and another to St. Paul, and another to St. William, and another to St. George; that is, his offices are distributed into so many parts, that hardly anything is left to him but a naked and empty name. They boast, indeed, of worshipping God alone; but when we come to what it belongs to God to do, they make as many gods as they have creatures, and distribute among them his power and authority. But the Lord has determined that these shall remain entire and uninfringed, and they cannot be conveyed to another without shocking blasphemy; for he alone does good to men, he alone defends and preserves them. The last clause of the verse expresses that knowledge which is derived from experience, that we may not seek salvation in any other than in him who its the only author of it. Hence we learn that the chief part of the worship of God consists in faith, when he is acknowledged to be the beginning and the end of life, when we bestow on him the title of Savior, and do not convey to another what he declares to belong to himself and to reside in him alone.

Footnotes

1 - "Ce suis-je, ce suis-je." "It is I, it is I."

2 - "Ce suis-je, ce suis-je." "It is I, it is I."

I, even I, am the Lord - The repetition of the pronoun 'I' makes it emphatic. The design is, to affirm that there was no other being to whom the name 'Yahweh' pertained. There was no other one who had the attributes which the name involved; there was, therefore, no other God. On the meanins of the word Yahweh, see the note at Isaiah 1:2.
And beside me there is no Saviour - There is no one who can deliver from oppression, and captivity, and exile, such as the Jews suffered in Babylon; there is no one but he who can save from sin, and from hell. All salvation, therefore, must come from God; and if we obtain deliverance from temporal ills, or from eternal death, we must seek it from him.

I, even I, am the Lord,.... Jehovah, the self-existing, eternal, and immutable Being; this is doubled for the confirmation of it, and to exclude all others:
and besides me there is no Saviour; either in a temporal or spiritual sense; the gods of the Heathens could not save them out of their present troubles, and much less save them with an everlasting salvation; none but God can do this, and this is a proof that Christ is God, since none but God can be a Saviour.

Lord--Jehovah.
saviour--temporally, from Babylon: eternally, from sin and hell (Hosea 13:4; Acts 4:12). The same titles as are applied to God are applied to Jesus.

The address now closes by holding up once more the object and warrant of faith. "I am Jehovah; and beside me there is no Savour. I have proclaimed and brought salvation, and given to perceive, and there was no other god among you: and ye are my witnesses, saith Jehovah, and I am God. Even from the day onwards I am so; and there is no deliverer out of my hand: I act, and who can turn it back?" The proper name "Jehovah" is used here (Isaiah 43:13) as a name indicating essence: "I and no other am the absolutely existing and living One," i.e., He who proves His existence by His acts, and indeed by His saving acts. מושׁיע and Jehovah are kindred epithets here; just as in the New Testament the name Jehovah sets, as it were, but only to rise again in the name Jesus, in which it is historically fulfilled. Jehovah's previous self-manifestation in history furnished a pledge of the coming redemption. The two synonyms הגּדתּי and השׁמעתּ have הושׁעתּי in the midst. He proclaimed salvation, brought salvation, and in the new afflictions was still ever preaching salvation, without there having been any zâr, i.e., any strange or other god in Israel (Deuteronomy 32:16; see above, Isaiah 17:10), who proved his existence in any such way, or, in fact, gave any sign of existence at all. This they must themselves confess; and therefore (Vav in sense equivalent to ergo, as in Isaiah 40:18, Isaiah 40:25) He, and He alone, is El, the absolutely mighty One, i.e., God. And from this time forth He is so, i.e., He, and He only, displays divine nature and divine life. There is no reason for taking מיּום in the sense of יום מהיות, "from the period when the day, i.e., time, existed" (as the lxx, Jerome, Stier, etc., render it). Both the gam (also) and the future 'eph‛al (I will work) require the meaning supported by Ezekiel 48:35, "from the day onwards," i.e., from this time forth (syn. לפני־יום, Isaiah 48:7). The concluding words give them to understand, that the predicted salvation is coming in the way of judgment. Jehovah will go forward with His work; and if He who is the same yesterday and today sets this before Him, who can turn it back, so that it shall remain unaccomplished? The prophecy dies away, like the massâ' Bâbhel with its epilogue in Isaiah 14:27. In the first half (Isaiah 42:1-17) Jehovah introduced His servant, the medium of salvation, and proclaimed the approaching work of salvation, at which all the world had reason to rejoice. The second half (Isaiah 42:18-43:13) began with reproaching, and sought to bring Israel through this predicted salvation to reflect upon itself, and also upon its God, the One God, to whom there was no equal.