OK, at personal risk of being torn apart by the resident unbelievers…
I was also an atheist. I spent 50 years of my life rejecting the thought of God because my childhood was unreasonably abusive, I found no evidence of God because of emotional pain. I eventually reached a point that I no longer wanted to live, and God revealed Himself to me. Do I hear voices, no. Can I explain it scientifically, no. I can only say that once I was able to submit to the concept of God and started to seek the truth, I found it. The truth is that there is a loving God that connects with us in different ways (three that I know of). It is a deeply personal adventure, one that no one can experience unless they want to. This is my experience, I thought Christians were nut cases too previously. Now I am one, and I am not ashamed.
To the question of the trinity…there is no mention of the word trinity in the bible from the searches I have done. The concept is clear, but also limited to our human experience and understanding. I am not convinced that someone that rejects God will ever understand, again that is from personal experience.