Accordingly our belief “God is three persons in one substance”. In this blog post written by a theologian Dale Tuggy is asked what “persons” and in this blog post by the same theologian is asked what is “substance”. I feel that now I cannot understand what is “substance”. Indeed it seems that I have a fairly good understanding what is “person”.

In our trinity statement of faith (“God is three persons in one substance”) a “person” means “somebody who speaks and hears”. A person is defined by what he speaks and hears.

(Psalms 2:7-9)
7 I will tell of the decree. Yahweh said to me, “You are my son. Today I have become your father.
8 Ask of me, and I will give the nations for your inheritance, The uttermost parts of the earth for your possession.
9 You shall break them with a rod of iron. You shall dash them in pieces like a potter’s vessel.”

Here God the Father speaks with God the Son. From this is clear that sayings and hearings of Father and Son are distinct. Father and Son are two different persons.

So, there are three distinct (different) persons of God.