Deeper Understanding of Isaiah 63:5(c-d) So My own arm brought salvation to Me,And My wrath upheld Me

Let's read Isaiah 63:5 together with Isaiah 59:16

Acts 4:12 states:

Salvation is found in no one else, for there is no other name under heaven given to mankind by which we must be saved.

Earlier in Isaiah 59:15, the Lord was displeased that "there was no justice and truth is nowhere to be found". Therefore the Lord determined to judge and bring salvation to His people. Isaiah 63:5c and 59:16c do not imply that the Lord needs his own salvation, rather, they means He desires to see His salvation realized. This is driven by the righteousness within Him that motivates His decisive action, for He is the only one that can complete the work.

The answer to this question involves the concept of "Theodicy", namely the judgement of God, or the Vindication of God. This is in the sense that God is being judged and must be vindicated. We see this often in the OT - see appendix below.

In the NT, we are told:

Rom 3:4 - By no means! Let God be true though every one were a liar, as it is written, “That You may be justified in Your words, and prevail when You are judged.”

Isa 63 is another perfect example of YHWH vindicating Himself in contradistinction from false gods who are "not gods at all" (Jer 2:11, 5:7, 16:20, 2 Kings 19:18, Isa 37:19, Acts 19:26, Gal 4:8, etc.) This is a constant theme of Isaiah's prophecies - that there is only ONE true God and that is YHWH (Isa 43:11, 44:6, 8, 45:5, 14, 18, 21, 22, 46:9, 47:10, etc.)

Thus we note YHWH's attempting to vindicate and save Himself of such accusations in Isa 63:

V1 Who is this coming from Edom, from Bozrah with crimson-stained garments? Who is this robed in splendor, marching in the greatness of His strength? “It is I, proclaiming vindication, mighty to save.”

V2 Why are Your clothes red, and Your garments like one who treads the winepress?

V3 “I have trodden the winepress alone, and no one from the nations was with Me. I trampled them in My anger and trod them down in My fury; their blood spattered My garments, and all My clothes were stained.

V4 For the day of vengeance was in My heart, and the year of My redemption had come.

V5 I looked, but there was no one to help; I was appalled that no one assisted. So My arm brought Me salvation, and My own wrath upheld Me.

V6 I trampled the nations in My anger; in My wrath I made them drunk and poured out their blood on the ground.”

I do not see any reference to the trinity in this passage (although that can be found in other places such as in Zechariah, but that is another question).

APPENDIX - Vindication of God

Quite often we see the idea of God being judged or placed on trial:

• Ex 7-12 – The Ten Plagues of Egypt. Pharaoh and his magicians refuse to acknowledge God and His supremacy. Each of the 10 plagues directly proved the impotence and deception of the Egyptian gods. Pharaoh and his defiant people punished by death of first born who would not trust in the blood on the door post. This vindicated YHWH as the only true God, especially after the false gods of Egypt are discredited.
• Ex 24 – the Golden Calf. Israelite worship of a cast golden calf idol was a direct challenge to God while Moses was receiving the 10 commandments whose principle provision was exclusive worship of Jehovah. People punished by destroying the golden calf and drinking contaminated water.
• Lev 10 – Nadab and Abihu. This incident was more a challenge of the priesthood but resulted in the immolation of the errant priests.
• Num 16 – Korah Dathan and Abiram. A very similar challenge of priesthoods as above resulted in the ground opening to swallowing the errant priests.
• Judges 3:7-11 – Othniel. Israel forgot God and served the Baals and Ashtoreth. God allowed Mesopotamian oppression but freed them when they returned to Him.
• Judges 10:6-11:33 – Jephthah. See Judges 10:14. Similar to above.
• Judges 16:23-31 – Samson. Similar to above.
• 1 Sam 4-6 – The sacred tabernacle Ark captured and returned to Israel in a way that showed the Philistines the much greater authority of Jehovah over their gods, especially Dagon.
• 2 Sam 11 & 12 - after David's appalling crimes of rape (of Bathsheba), murder of Uriah and then the attempted (but hopelessly failed) political coverup and lies, David is primarily accused of sinning against God (2 Sam 12:14, Ps 51:4) by discrediting the Name of YHWH.
• 1 Kings 17, 18 – Elijah on Mt Carmel. This is the quintessential contest of the gods to discover the true God. Baal and Ashtoreth are completely discredited as impotent, and their priests executed.
• 1 Kings 20 – Ahab vs Benhadad. See especially v13, 23, 28. This divine challenge was designed to dispel the notion that Jehovah was a local god of the plains or the mountains but was actually THE Universal God.
• 2 Kings 1 – Ahaziah’s sickness. Ahaziah is challenged by Elijah when he trusts the god of Ekron for healing instead of Jehovah. See v2-6.
• 2 Kings 5 – Naaman’s healing. See v15 where Naaman openly declares that “there no god in all the earth but in Israel.” Note the deliberate contrast with Ahaziah, and from a foreigner!
• 2 Kings 17 – Northern Israel captured. See v8, 14, 18 where this comes as a direct result of Israel’s refusal to serve Jehovah, and their trust of alien gods.
• 2 Kings 18, 19 – Sennacherib’s siege, boasts and threats. See 2 Kings 18:22, 19:5, 14, 22, 35. The unbridled boasting of Sennacherib and his belittling of Jehovah result in the death of 185,000 of his troops without Jerusalem even raising an army. Sennacherib humiliated and murdered on his return home and thus, vindicates YHWH
• Isa 44:6-28 – Idols vs Jehovah. This mocking poem openly derides impotent, lifeless, man-made idols and thus, vindicates YHWH as the only true God.
• Dan 2 – Nebuchadnezzar’s dream of the great statue. See v10, 11, versus 27, 28. The contrast between the ignorant (and non-existent) gods of Babylon vs Jehovah was stark – Jehovah reveals impossible mysteries. God and His servants/agents (Daniel and friends) are vindicated by the outcome.
• Dan 3 – Fiery furnace. Contrast v5 with v28. Nebuchadnezzar’s boast that no one could save them from his hand could not be left unmet. God and His servants/agents (Daniel’s friends) are vindicated by the outcome.
• Dan 4 – Nebuchadnezzar’s dream of the tree. This challenge is possibly the most common – self worship vs God worship. See v 30, 31 versus v37. God and His servants/agents (Daniel) are vindicated by the outcome.
• Dan 5 – Writing on the wall. Belshazzar defied Jehovah when he asked for the sacred vessels to be desecrated. See v2-4 vs v30. God and His servants/agents (Daniel and friends) are vindicated by the outcome.
• Dan 7 – Fourth kingdom and little horn. The fourth best and its little horn engage in blasphemous activities to defy God. Again, God and His servants/agents are vindicated by the outcome.
• Dan 8 – little horn from the Ram. Similar to above.
• Jonah 1 – The great storm of Jonah. Sailors realized that Jehovah had power over the elements and gave Him glory and worshipped, thus vindicating YHWH. See especially v5 vs 13-16.
• Acts 12 – Herod defied God by accepting human worship as a god. Herod is punished by a painful death and thus, God is vindicated. See v21-24.

In all these cases, someone either challenged God’s authority and power, or, people were asked to choose between the true God and a false god.

With respect to the OP’s second question, the context does not suggest that it is God who is in need of salvation but men. Note the use of the third person plural in Is 63:9.

Isaiah 63:9 NKJV

In His love and in His pity He redeemed them; And He bore them and carried them All the days of old.

The OP also asks, “As one reads Isaiah 63:5 (c-d), is there some sort of reference to the Trinity (Triune God)?” While there’s not a direct reference to the Trinity, Isaiah 63 in general and verse 5 in particular raise a number of questions that lend themselves particularly well to a Trinitarian answer.

Among both Jewish and Christian commentators, the identity of the figure with blood stained garments is a subject of some debate. The passage seems to anticipate this controversy with the question in v1: “Who is this who comes from Edom, With dyed garments from Bozrah, This One who is glorious in His apparel, Traveling in the greatness of His strength?” (Is 63:1).

Commentary of Ibn Ezra on Isaiah 63:1

Some refer this to Messiah, others to the angel Michael; but more correctly it may be referred to God.

Of the different interpretations, the two seen as relevant to this discussion posit the figure to be either 1) the Messiah or 2) God. The following excerpts are representative of these two views:

R. Moses Haddarsan in Bereshit Rabba in Genesis 49:11

"When the King Messiah shall come, he will be clothed in purple, beautiful to look at, which in colour shall be like to wine for the clothing of the King Messiah shall be silk, red as blood; and it shall be worked with the needle in various colours, and he shall be the Head of Israel; and this is what is said in Isaiah 63:1 "wherefore art thou red in thy apparel?" – quote taken from Gill’s commentary on Is 63:2

Keil and Delitzsch commentary on Is 63:1

The person approaching says that he is great in word and deed (Jeremiah 32:19). He speaks in righteousness; in the zeal of his holiness threatening judgment to the oppressors, and promising salvation to the oppressed; and what he threatens and promises, he carries out with mighty power. He is great (רב, not רב; S. ὑπερμαχῶν, Jer. propugnator) to aid the oppressed against their oppressors. This alone might lead us to surmise that it is God from whose mouth of righteousness (Isaiah 45:23) the consolation of redemption proceeds, and whose holy omnipotent arm (Isaiah 52:10; Isaiah 59:16) carries out the act of redemption.

Per Is 63:3-5, it is not just that the figure acts alone, but that it is his own arm that brings about the salvation that he seeks. If Isaiah 63 is indeed a Messianic prophecy, it raises crucial questions about the identity of the Messiah and how/where to draw the line between him and God. In my opinion, the difficulties in identifying the figure clothed in red are less problematic when viewed through the lens of a Trinitarian perspective.

Isaiah 6:5

I looked, but there was no one to help, And I wondered That there was no one to uphold; Therefore My own arm brought salvation for Me;

The passage depicts the different facets of God’s work of salvation. A change in tone/speaker occurs at v7 with a shift in focus to God’s mercy and to the presence/work of the Holy Spirit within/amidst the people of God. At v15 the passage again shifts its focus to one who is addressed as: “our Father; Our Redeemer from Everlasting” (Is 63:16). God is One who saves, but the different focuses/divisions in Isaiah 63 happen to align particularly well with a Triune view of God.