John Calvin Commentary Isaiah 63:5

"And I looked, and there was none to help; and I wondered that there was none to uphold: therefore mine own arm brought salvation unto me; and my wrath, it upheld me." — Isaiah 63:5 (ASV)

I looked, and there was none to help. Although the Jews lacked all assistance, and no one helped them by word or deed, yet he shows that the arm of the Lord alone is sufficient to punish enemies and to set his people free. Therefore, he shows that they ought to expect salvation from God alone, so that they may not look around in every direction, but may have their eyes entirely fixed on God, who does not need the help of others.

And I wondered. He portrays God as amazed that there is no one to offer him help when he desires to carry out his judgments. This is so that he may impress this doctrine more deeply on the minds of believers: God does not need human help, and he himself is sufficient to obtain salvation for his people.

Through this depiction, he further magnifies the help he had determined to give his people, partly to correct their lack of trust and partly to urge them to future gratitude. For God takes on a particular role when he describes himself as standing astonished, because this dullness truly characterized the Jews, who hardly believed what could not be accomplished by human power.

Therefore, he contrasts his own arm with all other forms of help, stating that its invincible power is sufficient for him, so that he may both be seen as their Savior and may scatter and defeat all the wicked.