Gaura Priya
IRL
Hi Madhuri, it's very easy to be thoroughly confused by the many and varied re-interpretations of, not only the doctrines of God the son, the Holy Spirit, and the Father,which go to make up the "trinity concept" but also nigh on every other biblical teaching, I'm sure you will agree. However if I may be so bold, it doesn't really matter what people who profess to be protestant, catholic or whatever title they give themselves "believe;" the scripture is the only authority on scripture, and the scripture states that it is not open to any private interpretation.
So to asnwer your question, if someone states that they do not "believe" in "the concept of the trinity" they simply don't yet have a clear understanding of the scripture, or, they have been subjected to inaccurate teaching about it. The good news is that this sort of topic isn't a Biblical guessing game for anyone committed to understandng these and other important Christian doctrines.
The Scripture does not even have the word 'Trinity' in it, so how can you say that it is Scripture under Scripture? When I read the Bible, I read it under a non-Trinitarian lens, because Jesus did not ask us to worship him, but to worship the Father; neither did he ask us to pray to him, but to pray to the Father in his name.
The Gospel is pretty clear to me... you can believe different if you choose to believe the Trinity, but I choose not to.