Without this understanding, our spiritual life can get discombobulated as attributes and functions of each member of the Trinity may be assigned to each, incorrectly.
The word Trinity is not found in the Scripture, but the concept is biblical. Historically, the formal doctrine of the Trinity derives from a succession of early church controversies and councils which sought to explain the biblical testimony regarding:
the oneness and unity of God in three persons;
the deity of Christ;
the personality and deity of the Holy Spirit.
The councils were in response to heresies such as Monarchianism and Arianism.
Modalistic Monarchianists believed there was one God who expressed Himself in three modes, not three distinct persons.
Dynamic or Adoptionistic Monarchian ists believed Jesus Christ was not God Incarnate but a deified man, an honorary god.
Arianism believed Jesus Christ had a different nature than the Father. The Son was created, not eternally preexistent.
The Council of Nicaea, A.D. 325, declared the Son to have the same nature as the Father.
The Council of Constantinople, A.D. 381, asserted the deity of the Holy Spirit.
In the intervening centuries ‘Trinity’ became a technical word for the three persons of the Godhead.
Rarely does a single passage of Scripture delineate point-by-point a complex doctrine. Rather, theologians formulate the principles of any major doctrine by comparing and correlating all related biblical passages. The believer accepts truth derived from many passages just as he would accept a biblical principle directly stated in a single context.
The doctrine of the Trinity is likewise formulated by combining all passages related to God the Father, God the Son, and God the Holy Spirit.
All that God has made known about Himself can be understood, Deut. 29:29, even the fact that He is singular in one sense and plural in another.
De 29:29 The secret things belong unto the LORD our God: but those things which are revealed belong unto us and to our children forever, that we may do all the words of this law.