We were created in the image of God, and to understand who we are, we need to understand who God is. His very character and nature are reflected through us. Unless we fully grasp who we are, we'll never become all God wants us to be.
Delighting in God is the message Tozer intended to be the follow-up to The Knowledge of the Holy. He demonstrates how the attributes of God--those things God has revealed about himself--are a way to understand the Christian life of worship and service. We are here to serve and adore him, but we can only fulfill that role by acknowledging who he is, which is the essence of the Christian life and the source of all our fulfillment, joy, and comfort.