The “true meaning of the three Persons of the Trinity”

…the reality of Christ was a clear mirror wherein the Sun of Truth—that is, the divine Essence—appeared and shone forth with infinite perfections and attributes. It is not that the Sun, which is the Essence of the Divinity, was ever divided or multiplied—for it remains one—but it became manifest in the mirror. That is why Christ said, “The Father is in the Son”, meaning that that Sun is manifest and visible in this mirror.

The Holy Spirit is the outpouring grace of God which was revealed and manifested in the reality of Christ. Prophethood is the station of the heart of Christ, and the Holy Spirit is the station of His spirit. It is thus evident and established that the Essence of the Divinity is absolute oneness and has no peer, equal, or likeness.

This is the true meaning of the three Persons of the Trinity. Otherwise, the foundations of the religion of God would rest upon an illogical proposition which no mind could ever conceive, and how could the mind be required to believe a thing which it cannot conceive? Such a thing could not be grasped by human reason—how much less be clothed in an intelligible form—but would remain sheer fancy. 

- ‘Abdu’l-Baha  (Table talks in Akka, authenticated by ‘Abdu’l-Baha; ‘Some Answered Questions’ – 2014 revised translation by the Baha’i World Center)