1. In his Word God says that he is beyond comparison. Read Isaiah 40:18-25. This section proclaims the incomparable greatness of God when likened to anything that human beings choose to call a god. At both the beginning and the end of these verses God is challenging the world to think up or create something that even remotely can be compared to him. In this connection read Exodus 20:4-6. In Luther's Catechism these words are used to form Luther's conclusion to the Ten Commandments. Here they serve as a further elaboration of the First Commandment.
    
What is Israel forbidden to do here?
Answer - Make some visible representation of the LORD their God.

Why shouldn't Israel make any image that is meant to represent God to them?
Answer - Because the true God cannot be represented in any visible way. His essence is beyond our ability to grasp and then portray in some material or logical way.

These passages do not specifically teach us that God is triune, but they do tell us not to expect that the true God is someone our finite minds are going to be able to comprehend or explain.

2. Read Deuteronomy 6:4-5. What is the primary truth set forth in these verses?

Answer - There is only one God, and he is the LORD.

Christians confess who they believe God to be in creeds like the Apostles' and Nicene Creeds. Old Testament Israel's creed was these verses. They confessed that there is only one God. That was a bold stand to take, and it made the Israelites different from all the polytheistic nations around them.

Read Exodus 20:3. The First Commandment also instructs God's people to only have one God. Jesus claims that this is a most important truth to remember.

Read Mark 12:29. This one God, the LORD, the holy God of Israel is the one Lord whom all believers are to trust, worship, love, and serve.

3. Read Isaiah 42:8-9; 44:6-8; 45:20,21; and 46:8-13. What is the common denominator in all of these passages?

Answer - Through Isaiah the LORD strongly insists that he is the one and only God and that his people should look only to him for their salvation.

As Christians we confess that God is one. We are monotheists, people who believe that there is only one God. We believe that because the Bible clearly reveals it.

4. Yet starting in the Old Testament the Bible teaches a certain plurality in the one God. Read Genesis 1:26-28. The Hebrew noun used for God here and everywhere else in the Old Testament is a plural noun, elohim. When God speaks in v. 26, notice the pronouns he uses for himself. They are plural.