This is an appeal to the personal identifiable God. He is known by his name. He is not merely a spiritual force. He is the God of the covenant with his people. When Moses was sent to Pharoah to release God's people from slavery, he told Moses that his name was "I AM WHO I AM. Tell them I AM sent you to them." The divine name YHWH (often pronounced as Yahweh) comes from the same Hebrew root H-Y-H ("to be"), reinforcing the idea that God is the ever-present, self-sufficient One.
Here's the link to St. John's Devotional Resources
