This is a very interesting topic to me. I was raised with belief in God but had strayed from practicing my faith for a time after a few years of marriage to a man who wanted nothing to do with belief in God. When I was having marriage issues (prior to my husband becoming an alcoholic), I prayed somewhat desperately to God and had the same experience you describe with no one else present. That was powerful to me. It was a life changing, unforgettable period of my life. I believe the presence of God within each one of us is equally powerful.
I was sincere, I believe that is always an important element of our HP working within us. I also believe in the power of positive thinking, etc., as well.