An American man has been found guilty of shooting and killing his atheist friend during an argument over the existence of god.

Thirty-three-year-old Douglas Yim shot Dzuy Duhn Phan six times during an alcohol and drug fuelled row at his home in Oakland California.

He also shot another friend Paul Park in the hand as he tried to stop the attack.

According to Park, the three men had been playing video games and taking drugs together. Yim became annoyed when Phan repeatedly asked Yim where God was every time he lost a game.

His annoyance turned to anger when Phan asked Yim where God had been when his father died of a stroke.

Yim threw his video game controller into his television, breaking the screen, before storming out of the room.

Phan followed him into the dining room and told him that if he wasn't going to calm down, he should get his gun and shoot him.

Yim then went to his bedroom, loaded his AR-15 assault rifle and returned to the living room where he opened fire.

During the trial he claimed he had acted in self defence because Phan was holding a black object, which he thought was a weapon, but was actually a mobile phone.

Prosecutor Allyson Donovan described the shooting as "extremely senseless".

"This clearly was a murder that was carried out in execution style," Donovan said.

Yim was convicted for first degree murder and faces 126 years to life in prison.