God (each has his or her own take on the definition ) indeed does exist in the capability of the human brain to formulate the concept. This is by way of many reasons eg indoctrination from a young age, being part of a cohesive group, fear of punishment or death, comfort by means of reward for capitulating to the demands of your god as outlined by other human beings to whom you cede responsibility for your life because they have told you they are qualified to do so.
In ancient times without the knowledge at our fingertips , and reasoning which we have by way of scientific evidence it is understandable that people would believe in 'gods ' as an explanation of the as yet unexplainable especially as demanded by the powerful who could use the concept of god to their advantage, however in our enlightened contemporary time imo to believe in the existence of God outwith that which exists in the electrical neurological mechanics of the human brain is an insult to ones intelligence and intellectual ability.