CCC 2810

In the promise to Abraham and the oath that accompanied it, God commits himself but without disclosing his name. He begins to reveal it to Moses and makes it known clearly before the eyes of the whole people when he saves them from the Egyptians: "he has triumphed gloriously." From the covenant of Sinai onwards, this people is "his own" and it is to be a "holy (or "consecrated": the same word is used for both in Hebrew) nation," because the name of God dwells in it.