essence

The “essence” of something refers to an indispensable quality without which the thing would not exist or be what it is. God’s essence refers to those qualities of God without which He would not exist or be God. For anything to be real (to have a real essence), it must be in a state of being. Accordingly, when philosophers talk about God being one in essence, they are referring to God existing in a state of pure being. The word “person” is different than “essence” in that it refers to a “subsistence”; it literally means “to stand under the essence.” So, the idea of the Trinity is that while God is one in essence (one in his beingness), there are three “subsistences” (persons) who stand under the essence of God’s beingness.