In different parts of the Old Testament, God is called by different names—for example, sometimes El and at other times Yahweh. Why is that? Why did God change names?
God did not change names but is simply too great to be confined to a single name.
In the ancient world and still today, to know someone’s name suggests a certain level of control over that person—in the same way that representing that person with wood, stone, or paint suggests an ability to know that person completely. God cannot be known as completely as we humans can know anyone else. Judaism forbids representing God directly; a burning bush is sometimes used.
The different names you noted—and others—reflect distinct theological traditions, including some of pagan origin. In the Scriptures, however, these variations are always understood within the faith tradition that begins with Abraham and Sarah. Centuries later, the Israelites (Israel means “let God contend”) finalized what we know as the first 11 chapters of the Book of Genesis.
The term El means “God” and is often connected with an attribute of God (El Shaddai, “all-sufficient one,” Gn 17:1) or some geographical place (El Bethel, Jacob’s dream at Bethel of angels descending from heaven, Gn 28:10–22). The name Bethel means “house of God.” Many names of persons or places end in “el,” signifying a relationship with God.
In some ways, the first five books of the Bible (Torah) are a single unit, but they reflect four theological traditions: Elohist, Yahwist, Deuteronomic, and Priestly. The last of these four, the Priestly, was finalized only in the sixth century before Christ.
The first account of creation (Gn 1:1—2:4a) comes from the Priestly tradition and emphasizes a single God’s supremacy and majesty in creation. The second account of creation begins at Gn 2:4b and reflects the Yahwist tradition that features a more intimate God, who walks in the Garden of Eden and converses with Adam and Eve.
Although the name Yahweh is used early in the Bible, it was, in fact, not introduced and accepted until the story of Moses’ dialogue with the burning bush (Ex 3:1—4:17). In time and out of respect, the Jews substituted the term Adonai (“Lord”) wherever the word Yahweh appears in the Scriptures.
Within a family, grandchildren who are cousins may sometimes use different names to refer to the same grandparent. A similar dynamic is at work among the various names for God in the Old Testament—all of them recognizing that no single name can totally encompass or describe God.