Wherever my wife and I have lived, we have always nailed to the doorpost of our home a little brass case called a mezuzah. It was a present from a Jewish neighbor and longtime friend in our apartment building in New York City. In it, written in Hebrew on sheepskin, are the words of Deuteronomy 6. Altogether, they are called the Shema, after the first Hebrew word in this verse: "Hear, O Israel: The LORD our God, the LORD is one."

This is one of the most basic confessions we make: the oneness of God, who revealed himself in creation, to the people of Israel, and most completely in Jesus Christ.

Jesus said, "I and the Father are one" (John 10:30). He was referring to his unity with the heavenly Father—and to their unity of purpose, their character of love, and their method of working. "Truly I tell you, the Son can do nothing by himself; he can do only what he sees his Father doing" (John 5:19).

The one true God is so different from the mythical gods of the nations around Israel. Myths are colorful tales that make for interesting reading, but one of the most obvious things about them is the quarreling and battling between various gods. They plot against and even try to kill each other.

The true God's teaching about himself, though, is simply this: "I am the LORD, and there is no other; apart from me there is no God" (Isaiah 45:5).