"The thing that makes the three members of the Godhead one is their shared essence or attributes. Each member of the Trinity, though a separate person, has the exact same representation of the attributes of the other members of the Trinity. They share these attributes equally, infinitely and eternally.
There are two errors we must avoided when describing the Trinity:
1. That the Godhead is composed of three distinct Persons, (i.e. Peter, James, and John, who are related to each other in the loose fashion by which men associate themselves together relative to certain ideals and principles). That supposition in the case of God would be “Tritheism” – three gods.
2. That the Godhead is one Person only and that the triune aspect of His Being is no more than three fields of interests, activities, and manifestations.
We will note the major attributes of God below, but the Westminster Catechism written in 1648 by the reformers is one of the best definitions given as to who God is: “God is a Spirit, in and of himself infinite in being, glory, blessedness, and perfection; all-sufficient, eternal, unchangeable, incomprehensible, every where present, almighty, knowing-all things, most wise, most holy, most just, most merciful and gracious, long-suffering, and abundant in goodness and truth”
The main attributes of God include:
Sovereignty, Righteous, Just, Love, Eternal Life, Omniscience (all knowing), Omnipotent (all powerful), Omnipresence (every where at the same time), Immutability (unchanging), and Veracity (absolute truth).
Each of theses attributes when combined make up the essence of God. Each of these attributes can be taught exhaustively individually, but we will save that for another day.
God’s Attributes are view in two groupings:
1. “Absolute Attributes”, which include: spirituality, infinity, and perfection.
a) Spirituality means God’s life and personality. God is immaterial, yet spirituality implies life. God is life, Jer 10:10; John 4:24; 1 Thes 1:9, and yet He does not possess life as we do, but He is life, He lives.
b) Infinity means self-existence, immutability, and unity. By infinity is meant that God is without boundary or limitation. He invented space and time and exists within and outside of these.
c) Perfection means truth, love, and integrity. The intellect, character and affections of God are perfect
2. “Relative Attributes”, which include:
a) Those related to time and space – eternity (God is not subject to time, He has always existed), and immensity (God is not subject to space).
b) Those related to creation – omnipresence (God is personally present everywhere), omniscience (God knows perfectly and eternally all that is knowable, whether actual or possible.), and omnipotence (God is all powerful, infinitely able to do all things within the range of His holy character or essence).
c) Those related to moral beings - veracity and faithfulness, mercy and goodness, and righteousness and justice.
From the various combinations of these main attributes we understand God to be, merciful, holy, just, faithful, good, kind, compassionate, gracious, grace, etc." (Rickard)