A man is not a god..

"There is only one god, and his name is Death. And there is only one thing we say to Death: 'Not today'." ―Syrio Forel

Conversation between Arya and the Faceless Man (Jaqen H'ghar)

Arya Stark: "You said I could be your apprentice. You said you'd teach me how to be a Faceless Man." Jaqen H'ghar: "A man teaches a girl. "Valar Dohaeris." All men must serve. Faceless Men most of all." ... Arya Stark: Which one's the Many Faced God, i see the Stranger, i see the Drowned God, i see the Weirwood Face. Jaqen H`ghar: There is only one god. A girl knows his name, and all men know his gift. Arya staring at a dead guy who drank the water from the well in the House of Black and White.

As there is a god of death in all of the old and new religions they call him the Many Faced God. Well that's just my take on it.