There is a joy which is not given to the ungodly, but to those who love You for Your own sake, whose joy You Yourself are. And this is the happy life, to rejoice in You, of You, for You. This is true joy and there is no other (Confessions, Book X. Sec. 22).First, notice that this joy has a very specific source or origin: loving God for His own sake. The implication is clear. There is no real joy from loving God for what one can get out of Him. That's the "ungodly" or pagan approach. Use the gods who use you.
But this God of Abraham, Isaac and Jacob is unlike any other god in the marketplace. "O LORD, God of Israel, there is no God like you, in heaven above or on earth beneath, keeping covenant and showing steadfast love to your servants who walk before you with all their heart" (1 Kings 8.23). He is not a "user" god. Instead, He is a God who loves, makes promises, and keeps His word; One who speaks with His mouth & fulfills with His hand (1 Kings 8.15, 24). In the words of C.S. Lewis,
“If God is love, He is, by definition, something more than mere kindness. & it appears, from all the records, that though He has often rebuked us & condemned us, He has never regarded us with contempt. He has paid us the intolerable compliment of loving us, in the deepest, most tragic, most inexorable sense” (The Problem of Pain).Second, observe that this joy is actually God Himself, fellowship with this God, loving and being loved by this God. It is the relationship that was experienced by Adam and rejected for a forbidden fruit. But it is a relationship Jesus has restored through His becoming fully human, holy living, death, burial, resurrection and ascension to the Father's right hand. "And this is eternal life, that they know you the only true God, and Jesus Christ whom you have sent. ( ... ) The glory that you have given me I have given to them, that they may be one even as we are one, I in them and you in me, that they may become perfectly one, so that the world may know that you sent me and loved them even as you loved me." (John 17.3, 22-23).
As I have often told my congregation, Jesus came to bring us back into that beautiful, loving embrace of the Father, the Son and the Holy Spirit. This is the place of true joy.