Trinity

Trinity means Tri-Unity - A group consist of three closely related members. The union of three divine persons, the Father, Son and Holy Spirit as one God. In other words  God in three persons. This is similar to a human made of Body, Soul and Spirit.

For simpler understanding of biblical truth about Trinity in a diagram:

    

 Why Trinity is important? Following taken from Billy Graham Association Website Q&A section:

Following are supporting verses for Trinity: