To deny the Trinity is to deny God and is a sin against the Holy Spirit, do not grieve the Holy Spirit!
No, it really isn't.
The trinity is never mentioned in the bible. And it is an unnecessary and misunderstood term.
It is not a prerequisite box in the checklist to salvation, that some believe in.
And it isn't what it is made out to be either.
There is a man called tertullian, who first used the term.
and he said that God and Jesus and the Holy Spirit have the same essence.
To be frank, Jesus and God have the same essence, and will, which is the spirit of holiness. They are both 'holy' beings, and both 'act' holy, and 'behave' holy, and encompass true holiness.
Denying man made doctrine through assertion of one's own common sense, and making up one's own mind, are things that everyone should do, and should be enabled to do without certain 'sects' telling them they are committing abominable sins for doing so.
The trinity is one man's perspective on how God and Jesus and the Holy Spirit co-encide (personified Holy Spirt).
Nothing more than that. But it has become practically law.
I disagree with most trinitarian doctrine, on the basis that it is man-fabricated, misunderstood, wrongly-taught, and most of the modern translation of it makes no sense, that and it seems to be part of some 'salvation checklist' and it's forced down peoples throats with phrases like 'it is required to salvation'.
Nonsense.
Even in the beginning of Christianity, people didn't believe nor even have heard of this 'trinity'. The Jews didn't believe it before Jesus came, and the people who were with Jesus clearly knew the difference between him and God.
God is one.
There is one God, and also one mediator between God and men; Jesus the Messiah.