When police arrived, the man stood up and stretched out his arms in a crucifixion pose, declaring "There are too many of us. I want to die!" one of the officers at the scene told the court on Tuesday, the second day of the trial.
The man admits to stabbing his two friends at the party in late 2011, but claims that he was psychotic at the time, and believed he would be reborn as Jesus.
One of the two friends, Andreas Nilstad (22), died after being stabbed several times in the head, chest and back. The other, Marius Løken (24), miraculously survived, despite being stabbed 15 times in the upper body.
On Monday, the man broke down in court and begged for forgiveness for what he had done.
"I want to tell the family of Andreas how incredibly sorry I am for what you are going through. I think about it every day," he told the court. "And Marius, I'm so sorry about what I've caused you, and that you are in pain. I've talked to mutual friends, who say that you are doing well, and I admire you for it."
If the court accepts that the accused was psychotic, it must then determine whether the psychosis was drug-induced, in which case the man could still be found guilty.
He had been smoking marijuana and drinking alcohol in the run up to his attacks.