"In the mystery of the Unity and Trinity of God we believe that, from all eternity and before material creation and even outside of time itself, the One God who desired a perfect communion of love expressed Himself in a perfect Word, containing all that He is. The Word God uttered was and is a perfect self-expression, also perfectly possessing what the Speaker possesses: being, omniscience, omnipotence, truth, beauty, and even personhood. So, from all eternity there were always two divine Persons, the God who spoke and the Word who was spoken, the God who Generates and the God who is Generated, true God with and from true God, Begetter and Begotten, Father and Son. There was never a time when this was not so. These two Persons eternally regard and contemplate each other. From all eternity they knew and loved each other, each offering the other a perfect gift of self-giving. Since the self-gift of these perfect and divine Persons, distinct but sharing one divine nature, can be nothing other than a perfect self-gift, perfectly given and perfectly received, the very Gift between them also contains all that each of the Persons have: being, omniscience, omnipotence, truth, beauty, and even personhood. Therefore, from all eternity there exist three distinct divine Persons having one indivisible divine nature, Father, Son and the perfect self-gift of love between them, the Holy Spirit."
Now I rejoice in my sufferings for your sake, and in my flesh I complete what is lacking in Christ’s afflictions for the sake of his body, that is, the Church, of which I became a minister according to the divine office which was given to me for you, to make the word of God fully known, the mystery hidden for ages and generations but now made manifest to his saints. To them God chose to make known how great among the Gentiles are the riches of the glory of this mystery, which is Christ in you, the hope of glory. Him we proclaim, warning every man and teaching every man in all wisdom, that we may present every man mature in Christ.—Colossians 1:24-28