I was diagnosed with Narsisstic personality disorder(NPD), the proper term for some who has a "God Complex" is a rare mental disorder characterized by an inflated sense of self-importance, entitlement, a deep need for admiration, and an alarming lack of empathy for other people.Feeling superior is a natural feeling that is relative to the person,some people might feel less or more important depending on their LMS(Looks,money,status),these three can relatively decide the color and shape of your life, either life will be bitter or sweet for you.
Let me ask you a quick question...Do you know the origin of the word Narcissus ? According to the Greek Mythology,Narcissus was a hunter and was famous for his beauty,and the legend says that Narcissus rejected anyone who loved him or admired him, as he only cared about himself.
The Greek Myth continues with the narration that the gods noticed Narcissus Vanity and took him to the lake, and there, on the lake's water reflection,he kept admiring hes reflection on the lake,the degree of his love for his image made him refuse to leave his place and kept contemplating the image until he died.
The Media, culture, and anime... In this one,I will be talking about anime to be more precise.Anime fueled my belief in superiority over the Human race.I will not be able to list all the factors that influenced and strenghthened my beliefs,I will only talk about some of the Anime characters that affected me during my childhood.

Ken Ichijouji From Digimon Genius is typically a powerful tool for those who have a god complex, but high intellect is often responsible for its development too. As it the case for Ken Ichijouji. Essentially, because of his sharp mind, he believes that he is the only one worthy of entering the digital world, and then proceeds to assume direct control of digimon via his dark rings.

Ryuga From Beyblade Ryuga is because of his Legendary Blader status and the fact that his power is so great that an island colony believed that the phenomenon caused by his abilities was from a God.

Terumi Afuro From Inazuma Eleven Heaven's Time God Knows

Lucemon From Digimon Lucemon is the main antagonist of the Digimon anime Digimon Frontier, as well as a major antagonist in Digimon Fusion. His name is based on Lucifer, more commonly known as The Devil/Satan/Lucifer within the beliefs of Abrahamic religions.

The Truth From Full Metal Alchemist It is a symbolization of God and knows all things about the world. One quote from this character is "I am the called by many names; I am the world, I am the universe, I am god, I am truth, I am all, I am one, and I am you."

Griffith From Berserk Griffith is quite psychopathic, manipulative and obsessive to the point that he was willing to strike Guts down than to let him go when the larger man muses about leaving.

I didn't list all the characters just to let you know...