I think many people feel the doctrine of the Trinity won’t bring delight because the Trinity seems like an obscure theological add-on to who God is. God is spoken of as the “blessed” God, or the “happy” God, in 1 Timothy 1:11. Which God are we talking about? The blessed or happy God is only the triune God. You will share His blessedness or happiness when you know Him. The Trinity is not an obscure doctrine for professional theologians only; the Trinity is a description of who God is as Father, Son, and Spirit.
What does that actually look like? In pressing in to know the living God, let’s start with John 20:31. John says he has written these things “so that you may believe that Jesus is the Christ, the Son of God, and that by believing you may have life in his name.” Jonn is calling you to faith in Jesus, but that faith in Jesus, the Anointed One, the Christ, the Son of God, shows you that when you come to Jesus, you’re taken to a triune God. He’s the Son of the Father, anointed with the Spirit.
When you come to Jesus, you are introduced to a God you never dreamed of. You might have thought God was a monstrous boar and tyrant in heaven whom you would never be interested in. You might have to serve Him, but maybe you didn’t want to. You see in Jesus, however, that God is a father, the sort of Father who has eternally been loving His Son and who has so enjoyed His Son that He wanted His Son to be the firstborn among many brothers. Pressing in through Jesus to know the triune God is the only way to see that God truly is delightful.
You will not find joy like that in another god, such as a single-person god. What is a single-person God motivated by? That god has always been by himself, so he’s not motivated by love. Only the triune God—the Father who has loved the Son for all eternity—can be rightly described by the words “God is love.”
The triune God will be gracious even to sinners and give them a blessing in His gospel that no other god could give: adoption. A god who is not Father, Son, and Spirit could not adopt us as children. Pressing into the Trinity is the oxygen of Christian joy and healthiness. It is knowing the living God better.