The Holy Trinity is an important doctrine of the Christian Church. Three Persons, One God: God the Father, Son and Holy Spirit, eternally together and yet separate persons. Without upholding the Trinity, one cannot be a “Christian.” A person may believe in God. A person may believe in Jesus, either as a great man or as a divine being of some sort. A person may even believe in the wonders of the Holy Spirit. However, if one does not believe in the orthodox concept of the Trinity, then one cannot be a Christian. Hence, the Mormons and Jehovah’s Witnesses, can claim that they are “followers” of Christ, but the title “Christian” cannot bestowed on those groups because of their different theological understanding of the Trinity.
Nevertheless, the Trinitarian theology is not an easy one to understand nor grasp completely. It is one of those mysteries of faith. However, the Hebrew Scriptures and the New Testament are filled with readings that clearly allude to the Trinity, although the word itself is never seen anywhere in the Holy Bible.
There are many heresies that still exist today that confuse the Trinitarian formula to their adherents, even in some groups disguised as traditional “Christian” churches. To claim that the Father, Son and the Holy Spirit (some groups prefer to say Creator, Redeemer and Sustainer, to escape the masculine language), are not equal in power and essence of being one God, yet are distinct separate persons, is to fall into a heresy. The Three Persons of the One God-head have and continue to work together as equal persons, as one God, in the work of creation, redemption and sustaining.
The Holy Trinity is not up for negotiation. This is an important theological precept of the Christian Church. As stated earlier, you can be many things, but you can’t be an “orthodox” Christian, if you don’t believe in the Trinity.
For example, the Unitarians, who eventually broke off from the Melchiorites in the 1800s, believe in God being just the Father, with Jesus being a mere human being. The Unitarians are a respectable group, for they clearly call themselves unitarians because they deny the Trinity. They at least don’t try to “hide” or drag others into a heresy.
There are many attractive teachings and thoughts today, and one is free to believe one wants. However, Christians should be educated and know how to distinguish orthodoxy from heresy. The Trinity is an absolute foundational doctrine to Christianity.