What is Trinitarianism?

Trinitarianism is the theological belief in Christianity that God is a Trinity. The Trinity is the teaching that there is only one God in all existence and that God exists in three distinct, simultaneous, co-eternal, co-powerful persons known as the Father, the Son, and the Holy Spirit. Trinitarianism is strictly monotheistic (there is only one God in all existence). 

The term, person, is used to designate the attributes of each of the members of the Trinity having attributes such as wills, being able to love, to hate, to speak, to recognize the existence of others, etc.

The Trinity is one of the defining doctrines of Christianity. All true believers will come to accept the doctrine of the Trinity because that is what the Scriptures teach. So, the Trinity is a necessary Christian theological position, but sometimes it takes discipling and teaching before someone would come to accept the doctrine once he or she has become Christian.

Called GodPhil. 1:2John 1:1, 14, Col. 2:9Acts 5:3-4
CreatorIsaiah 64:8John 1:3, Col. 1:15-17Job 33:4, 26:13
Resurrects1 Thess. 1:10John 2:19, 10:17Rom. 8:11
Indwells2 Cor. 6:16Col. 1:27John 14:17
Everywhere1 Kings 8:27Matt. 28:20Psalm 139:7-10
All knowing1 John 3:20John 16:30, 21:171 Cor. 2:10-11

The term, "trinity," does not occur in the Bible. But the concept is taught. Just as monotheism is taught in the Bible, the term, "monotheism," is not found. So, a word does not have to be found in the Scriptures in order for the concept to be taught.