The Bible says that “the heavens declare the glory of God,” and one glimpse of a starry night far away from city lights will convince you that the One who cast the stars across the galaxies must indeed be glorious. But how can we as feeble and finite creatures describe or comprehend the glory of God?
Perhaps we can begin by saying that “glory” is intrinsic to the being of God. If, as our Shorter Catechism reminds us, God is a spirit, Infinite, eternal, and unchangeable in his being, then surely this God is transcendent and far above us. We see his nature revealed in the splendor of his attributes, and in them we see one glory upon another. God is glorious in his might, glorious in his grace, and glorious in his holiness. All of his personal attributes cry out, “Glory!”
Glory however is a reflexive attribute. To be realized it must be seen and witnessed. “The heavens declare the glory of God,” and we should respond to that revelation of glory by affirming and testifying to it. If we as creatures can in a creaturely way reflect the glory of God, then it is uniquely the case that the three persons of the Trinity May reflect and give glory to each other.
In John 17, Jesus prayed that the Father would glorify the Son so that the Son might in turn glorify the Father. There is a mutual interest in magnifying the persons of the Trinity from within the trinity. The glory of the Father is proclaimed and magnified by the Son. The glory of the Son is appreciated and loved by the Father. The Spirit delights in glorifying the Son.
By contrast, if you deny the trinity of persons in the Godhead and assert that God is unipersonal, then such a Unitarian God will never know the nature of true glory. The god of Islam or the god of the Jews or the god of mainline Protestantism is a Unitarian God. They deny the full deity of the Son, or deny the distinctions within the Godhead, blending the Son into the Father and the Spirit and indeed into all of reality.
Such a Unitarian God is incapable of reflecting and revealing glory. Glory is much like love and communication. For them to exist, there must be a distinction in persons. There must be an Other to be loved or spoken with. In the realm of eternity prior to the existence of anything else, “God” must be a Trinity of persons to fully realize and reveal glory. A Unitarian God cannot know love because there is no other person to which such a god can give himself or herself to. Similarly, no Unitarian God can communicate, since there is no one else to communicate with.
How can a Unitarian God that is incapable of love and communication arise to create the heavens and the earth in all their complexity and wonder, including the wonders of love, communication, and glory? It is impossible, and therefore any Unitarian God is no God at all. Only the trinity is intrinsically glorious and reflexively glorious. It is our delight to explore and have communion with this glorious God in the three persons of the Trinity, the Father, the Son, and the Holy Spirit.