What is God?
God is a Spirit, infinite, eternal, and unchangeable in his being, wisdom, goodness, holiness, truth, justice, and power
The Holy Trinity
The term trinitas was first used by Tertullian (155-240).
Only one, the true and living God (Deut 6:4)
There are 3 Persons in the one God: the Father; the Son; and the Holy Spirit (1 Pet 1:2; Matt 28:19-20; 2 Cor 13:14)
The Father is begotten of none nor proceeding from none; the Son is eternally begotten of the Father; the Holy Spirit is eternally proceeding from the Father and from the Son.
The ontological equality: the 3 Persons are the same in substance, equal in power and glory.
The Decree of God
God’s decree means God’s eternal plan
Eph 1:11 In him we were also chosen, having been predestined according to the plan of him who works out everything in conformity with the purpose of his will
Ps 33:11 But the plans of the LORD stand firm forever, the purposes of his heart through all generations
The basis of God’s decree is his will
The goal of God’s decree is his own glory