God is simple. Distinct relations (which are the persons) do not import composition.Does the Roman Catholic Church believe that God’s Essence isn’t truly distinct to the Divine Persons? If so, how are the Divine Persons truly distinct from one another when they aren’t really distinguished from the Essence?
http://www.vatican.va/archive/ccc_css/archive/catechism/p1s2c1p2.htm251 In order to articulate the dogma of the Trinity, the Church had to develop her own terminology with the help of certain notions of philosophical origin: “substance”, “person” or “hypostasis”, “relation” and so on. In doing this, she did not submit the faith to human wisdom, but gave a new and unprecedented meaning to these terms, which from then on would be used to signify an ineffable mystery, “infinitely beyond all that we can humanly understand”.82
252 The Church uses (I) the term “substance” (rendered also at times by “essence” or “nature”) to designate the divine being in its unity, (II) the term “person” or “hypostasis” to designate the Father, Son and Holy Spirit in the real distinction among them, and (III) the term “relation” to designate the fact that their distinction lies in the relationship of each to the others.
253 The Trinity is One . …
254 The divine persons are really distinct from one another. …
255 The divine persons are relative to one another . …
St. Thomas Aquinas, Summa Theologiae, First Part, Question 39, Art. 1.“I answer that, The truth of this question is quite clear if we consider the divine simplicity. For it was shown above (Q[3], A[3]) that the divine simplicity requires that in God essence is the same as “suppositum,” which in intellectual substances is nothing else than person. But a difficulty seems to arise from the fact that while the divine persons are multiplied, the essence nevertheless retains its unity. And because, as Boethius says (De Trin. i), “relation multiplies the Trinity of persons,” some have thought that in God essence and person differ, forasmuch as they held the relations to be “adjacent”; considering only in the relations the idea of “reference to another,” and not the relations as realities. But as it was shown above (Q[28], A[2]) in creatures relations are accidental, whereas in God they are the divine essence itself. Thence it follows that in God essence is not really distinct from person; and yet that the persons are really distinguished from each other. For person, as above stated (Q[29], A[4]), signifies relation as subsisting in the divine nature. But relation as referred to the essence does not differ therefrom really, but only in our way of thinking; while as referred to an opposite relation, it has a real distinction by virtue of that opposition. Thus there are one essence and three persons.”