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God’s Word for You

Isaiah 1:24-25 The merciful Triune God

by Pastor Timothy Smith on Wednesday, December 27, 2023

24 “Therefore,” declares the Lord, the LORD of Armies, the Mighty One of Israel: “Ah, I will surely get relief from my enemies. I will avenge myself on my foes. 25 I will turn my hand against you. I will smelt away your dross as with lye and remove all your impurities.

“Declares” in this case is the word ne’um, which occurs mostly in the prophetic books and parts of the Old Testament. Here in Isaiah, the twenty-five occurrences can be at the beginning, middle, or end of a prophetic oracle. In Isaiah, the Lord is always the speaker. Sometimes it introduces a powerful law proclamation: “‘What do you mean by crushing my people and grinding the faces of the poor?’ declares the Lord, the LORD of Armies” (3:15). Other times, it introduces a tender gospel message: “‘Do not be afraid, O worm Jacob, O little Israel, for I myself will help you,’ declares the LORD, your Redeemer, the Holy One of Israel” (41:14). Often it reminds us of God’s glorious holiness and supreme justice as he speaks, which is part of the message here in the first chapter.

In addition to this, we can’t help but notice the threefold naming of God: The Lord, the LORD of Armies, and the Mighty One of Israel. The Bible’s teaching about the triune nature of God, the Holy Trinity, runs all throughout the Bible, but is explained more fully and completely in the New Testament. It is the main subject of the great Athanasian Creed but is included in the other ancient creeds and all of the Lutheran Confessions. The doctrine of the holy Trinity consists especially in this: “We worship one God in three persons and three persons in one God, without mixing the persons or dividing the divine being. For each person—the Father, the Son, and the Holy Spirit—is distinct” (Athanasian Creed).

The Athanasian Creed defines the Trinity in the fullest and most concrete terms. Johann Gerhard proposed several theses about the Trinity that thoroughly defend the teaching and are well worth repeating:

1. All who are to be saved must know and believe the mystery of the Trinity.

This is illustrated by many things spoken by Jesus and his apostles. “No one knows the Son except the Father, and no one knows the Father except the Son and anyone the Son wants to reveal him to” (Matthew 11:27). And John says: “No one who denies the Son has the Father” (1 John 2:23), and again: “Whoever does not abide in the doctrine of Christ does not have God” (2 John 1:9).

2. The mystery of the Trinity should not only be taught thetically (point by point) in the Church but should also be disputed antithetically (error by error) against its assailants.

God is described “as a father” (Deuteronomy 1:31; Psalm 68:5), but he is also specifically called Father: “You are my Father, my God” (Psalm 89:26); “Have we not all one Father? Did not one God create us?” (Malachi 2:10). The Spirit of God, or Holy Spirit, is also frequently shown in the Old Testament (Genesis 1:2), especially as the author of life and of our faith: “The Spirit of God has made me; the breath of the Almighty gives me life” (Job 33:4). In this thesis, Gerhard also shows that when errors about the Trinity are encountered (such as happens when people enter into classes to join our churches), these should be addressed and exposed one by one and not permitted to stand, since they are all obstacles to saving faith in Christ.

3. The mystery of the Trinity ought and can be proved not from the streams of the church fathers nor from the muddy puddles of the scholastics but from the clear fountains of the Scriptures.

It is admitted even by enemies of the church like Socinus that the doctrine of the Trinity is not a late addition to the teachings of the church, but has always been a central teaching, for he said, “We can concede… that all Christians worshiped the Triune God since apostolic times,” and this is seen even in the three articles of the Apostles’ Creed. But Gerhard is wise to point to Scripture for proof rather than to quotations from the faithful. The Trinity is seen most clearly at the Lord’s baptism (Matthew 3:16-17), in the sayings of Jesus mentioning all three Persons (John 15:26), and the formula for baptism (Matthew 28:19).

4. The mystery of the Trinity can and ought to be confirmed not only from the New Testament but also from the Old.

Many New Testament passages are clear enough, such as Paul’s benediction: “May the grace of the Lord Jesus Christ, and the love of God, and the fellowship of the Holy Spirit be with you all” (2 Corinthians 13:14). But we must remember those verses that declares the unity or oneness of God (“I and the Father are one” John 10:30), and those that proclaim the distinct persons of the Godhead: “God said, ‘Let us make man in our image, in our likeness’” (Genesis 1:26). And the great creed of the Old Testament church did both: “Hear, O Israel, the LORD our God, the LORD, is one” (Deuteronomy 6:4).

The verse before us, Isaiah 1:24, does the same thing, by describing God as the Lord, the LORD of Armies, and the Mighty One of Israel. There are three names, and yet one God. For Isaiah also says, “Before Me no god was formed nor will there be any after Me” (Isaiah 43:10).

In our verse, the Lord declares that he will get relief for himself by punishing, taking vengeance, on his foes. Who are the foes of God? All who deny him and who oppose him, everyone who does not put their faith in him. Therefore it is not necessary to determine whether God is speaking here to the nation of Israel or to Israel’s enemies, since everyone who rejects Christ is the enemy of God, no matter what their ancestry. “Oh what audacity! Oh what madness! You runaway slave, you incorrigible slave, do you rebel against the good Lord?”

But God adds his eternal compassion to this judgment: “I will smelt away your dross as with lye and remove all your impurities.” Lye or potash is the ashes of wood, charcoal or burnt plants, used for cleaning (Jeremiah 2:22; Job 9:30) or here for smelting. When God destroys sin in a man without faith, there will be nothing left; that man will be condemned, body and soul, to suffer in hell forever. But when God purifies and destroys sin in anyone who has faith in Christ, then Christ will preserve his soul and raise his body from the dead, and he will join God forever in heaven, stainless, sinless, refined, purified, and forgiven. This is God’s compassion and mercy—his mery that endures forever.

In Christ,
Pastor Timothy Smith

Pastor Tim Smith
About Pastor Timothy Smith
Pastor Smith serves St. Paul’s Lutheran Church in New Ulm, Minnesota. To receive God’s Word for You via e-mail, please visit the St. Paul’s Lutheran Church website.


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