This happened during my college days.One day I returned to my room from a local library,heard loud voices in my room. Two of my room mates were arguing about something. It seemed that they were arguing for a long time. After few minutes of observation,I learned that they were arguing about whether God exists or not. I had to leave the room for some other work and wanted to settle the argument before I leave. I asked one guy, what was his point. He told that he was on God's side. I told him for everything there is a source or a cause and our parents were the source for us. I asked him,what was the source for God. When he was searching for the answer, I turned to the other guy.I asked him If God doesn't exist, who created the Earth,Sun and the entire universe and there must be some source. I finished my speech saying,"So God exists for the believers and doesn't exist for the non-believers!". As I was leaving the room, I heard one of the two, telling the other,"Ipch,we were arguing for one hour, this guy came and disrupted everything."