Fully God in Each Person, No Division

Question #12: If Father, Son, and Holy Spirit are each fully God (Council of Florence, DS 1330–31) and thus identical with the divine essence, how does Catholic theology maintain their genuine personal distinction while upholding simplicity?

Catholic theology, following the Council of Florence (DS 1330–31), teaches that Father, Son, and Holy Spirit are each fully God, meaning they possess the entire divine essence without partition. At the same time, the Church insists on genuine personal distinction among the three Persons, all the while upholding divine simplicity—the doctrine that God’s essence has no composition or “parts.” The key to reconciling these truths lies in understanding that the three Persons differ not in the essence they share but in their relational identities or “modes of origin.”

  1. Each Person is Fully and Wholly the One Divine Essence
    Because God is simple, the divine essence cannot be divided into parts—so the Father does not possess “one-third” of the essence, nor the Son or the Holy Spirit. Instead, each Person is the fullness of God. Thus, the Father is God, the Son is God, and the Spirit is God, without implying three gods. The shared essence is absolutely one, undivided, and infinite.
  2. Distinct Relational Identities
    Catholic tradition explains that the Persons differ according to their mutual relations within the Godhead:
    • The Father is unbegotten and eternally begets the Son.
    • The Son is begotten by the Father.
    • The Spirit proceeds from the Father (and, in Western theology, from the Son as well).
    These relations of origin (begetting, being begotten, proceeding) do not introduce “parts” into God. Rather, they are subsistent relations, fully divine, marking how the one essence is possessed. In this way, the Father is not the Son or the Spirit, the Son is not the Father or the Spirit, etc. These distinctions are real yet do not fracture the essence.
  3. No Division in the Essence, Only Personal Otherness
    Because each Person is the divine essence, there is no composition of “essence” plus “Person” as two separate components in God. Rather, a Person is the manner in which the essence subsists—“Father,” “Son,” or “Spirit.” Consequently, personal distinction exists strictly at the relational level (who begets, who is begotten, who proceeds), not by carving up the divine nature.
  4. Upholding Simplicity
    In this framework, God remains absolutely simple: one infinite act of being, undivided and wholly present in each Person. Rather than multiplying God, the real distinctions among the Persons show how the one, simple essence is fully actualized in three irreducible relational identities. Each Person is therefore fully God, while each remains personally distinct—preserving both Catholic teaching on the Trinity and the doctrine of divine simplicity.
  • John 10:30 – “I and the Father are one.”
  • 1 John 5:6 – “The Spirit is the truth.”
  • Matthew 28:19 – “…baptizing them in the name of the Father and of the Son and of the Holy Spirit…”
  • John 1:1 – “In the beginning was the Word…”

(see questions #11, #14, #15 for more)