The most I can truly know is that I exist. I can not know with absolute certainty that anything or anyone else exists. If nothing else exists then I must be the de facto Supreme Being of my own universe. In other words, a Supreme Being exists, even if it is just me.
There is no plural of “I”. “We” is not a multiple of “me”. All experience necessarily comes via self. A person, no matter how many others there may be, is the center of his own universe. Each person is his own Supreme Being. This is not out of pride or vanity but an unavoidable quality of self. He must take it completely on faith that other people and other things exist. Sensations are evidence but not proof.
The term “God” comes with many connotations. In my argument I use “Supreme Being” because it’s meaning is exactly what it suggests – a being that is supreme. However, if I consider the many other connotations of “God” such as being omnipresent, omnipotent and omniscient it is interesting to note that the “Supreme Being” in my description may share these attributes as well. If there is in fact only me, I am omniscient because I possess all knowledge. I am omnipresent because my “here” is the only place to be. I am omnipotent because all power resides within me.
I have faith that other people and other things exist, including and especially God with all of His wonderful connotations. But I can know this: if I am wrong, then at the very least God exists if only within me.