The song of Isaiah 12 actually forms the last part of a long subsection beginning in Isaiah 7. Isaiah is sent to Ahaz in the face of an impending invasion from Syria and Israel to tell him that they will come to nothing. Ahaz, however, does not believe, even when the Lord invites him to do what is normally forbidden by testing the Lord (Isaiah 7:12). God gives the sign of Immanuel both as a promise of future deliverance in Christ (Matthew 1:23) but also to show faithless Ahaz that He will still do what He said by bringing the invasion to nothing (Isaiah 7:16). However, the Lord declares that Assyria will come to sweep faithless Judah away (Isaiah 7:17-20).
Though Assyria will wipe away Judah, yet God will also bring Assyria into judgment, a promise which He emphasizes beginning in Isaiah 10. Even though God will send His people away into exile, He will also bring them back (Isaiah 10:20-23). The righteous Branch, that is, Christ will come forth “from the stump of Jesse” (Isaiah 11:1), the seemingly dead remains of the tree of the house of David. Jesus will be “a signal for the peoples” and “in that day the Lord will extend His hand yet a second time to recover the remnant that remains of His people” (Isaiah 11:10-11). Just as the Lord would bring back His people from exile, so He would also gather together His people from all the ends of the earth.
This, then, is the greater context for Isaiah 12. “In that day,” that is, in the day when the Lord gathers His people in the second time, “I will give thanks to You” (Isaiah 12:1). This is closely related to last week’s reading in Lamentations 3, where Jeremiah declared his hope in the Lord even in the face of the Lord’s wrath. God will turn away from His fierce anger which lasts but a moment and bring His favor which has no end (Psalm 30:5; Job 13:15).
Isaiah 12:2 is unusual in that the Lord’s name is repeated twice in a row, first in a shortened form and then in its usual fuller form. The NKJV renders it the most literally: “For Yah, the LORD, is my strength and song.” This form also occurs in Isaiah 26:4. Perhaps this doubling is used for emphasis, especially since both references speak of the Lord as “strength.”
The imagery of “water from the wells of salvation” finds important parallels in passages like John 4 where Jesus speaks of living waters to the woman of Samaria; John 7:37-19 where He speaks of the Holy Spirit as “rivers of living water”; Ezekiel 47:1-12, where the prophet sees the river which flows forth from the temple; and Revelation 22:1-5, which speaks of the river of life in New Jerusalem. On that day, when the believer draws water, he will call upon the name of the Lord and praise Him for what He has done (Acts 2:21; Romans 10:13; 1 Chronicles 16:8; Psalm 9:11; 105:1).
Two other words are noteworthy in this text. The first is “gloriously” in Isaiah 12:5. This word has the most basic meaning of “rising,” and it is used in this sense in Isaiah 9:17 where it describes smoke rising into the sky and in Psalm 89:8 where it describes the raging of the sea. Both a column of smoke and a raging sea bring to mind a sense of awe, a rising that brings with it a sense of power. It can also describe the rising of pride, that is to say, presumption and arrogance, as it is used in Psalm 17:10. But the word is most often used to describe the exaltedness and the “rising” of God: Psalm 93:1; 110:6; and Isaiah 26:10. If the sea and smoke are exalted, how much more so the Lord!
The other is “cry aloud” or “shout” in Isaiah 12:6. It is used in several other places, like Isaiah 10:30; 24:14; 54:1; Jeremiah 31:7; and Esther 8:15. But its most colorful usage and the one which shows its most basic meaning occurs in Jeremiah 5:8 and 50:11, where it describes the cry of stallions. While the translation “to neigh” doesn’t make much sense in relation to men, it is an extremely intense shouting, much like a stallion crying aloud. Perhaps it is related to the loud whinnying of a horse who sees a long lost companion returning.