The instructions David Charles Edgerley says he could hear coming from the TV and radio were clear.
"Burn, burn, burn," Edgerley told Brisbane Supreme Court on Tuesday.
Edgerley, 39, is on trial for murder after dousing Victor Graveson's bedroom in petrol and setting it alight as the 65-year-old housemate slept, holding a door closed to ensure there was no escape.
Mr Graveson was taken to hospital in a critical condition with burns to 80 per cent of his body but died three days later.
"I remember ...the TV and the radio kept telling me to burn, burn, burn - I was trying to follow instructions they were telling me," Edgerley told the jury.
However Edgerley said he had no intention of killing Mr Graveson, only to create a diversion for his escape from the Alexandra Hills residence and his "dangerous" housemate.
Edgerley said he had "paranoid thoughts" that he was in his own TV program like the Truman Show where "everyone were just actors" who constantly followed and watched him after a near fatal 2012 machete attack.
Since recovering from the attack Edgerley said he also believed that God had brought him back to life with the "spirit of Jesus inside me" and that he could heal people.
He was also convinced that he was a member of the British Royal Family and his grandmother was the Queen.
When he moved in with "underworld figure" Mr Graveson in September 2017, Edgerley's mental state went into a downward spiral exacerbated by drug use and a decision to stop taking his medication, the court heard.
Edgerley said he had heard voices in the TV and radio telling him "Victor was going to get him" and "watch your back" after he witnessed Mr Graveson assault a woman with a screwdriver.
In a fragile state of mind, Edgerley said he decided to flee the home early one morning as more voices appeared.
"I heard my niece's voice calling for help, I thought she was in trouble," Edgerley said.
"Shortly thereafter I had Mum's voice in my head telling me I was a good boy.
"I remember going inside ... and the TV was saying burn it, burn it ... I threw the petrol in (Mr Graveson's) room ... lit the floor on fire and turned and ran.
"I was scared. I was trying to create a distraction ... to get away."
Edgerley said he tried to lock the door outside as he saw Mr Graveson emerge from the bedroom.
"I saw Victor coming from the room running towards me ... to me he wasn't on fire or anything like that and I turned and ran," he told the jury.
"He (Mr Graveson) ran the Redlands (Brisbane area), it was his backyard - I was thinking 'he is coming for me'."
Edgerley said in hindsight his actions are "hard to explain".
"I wasn't thinking. I had no idea what I was doing," he said.
The incident was the result of a "perfect storm of events", his defence barrister said.
"His downward spiral from drug use and his mental state, the environment he was in ... led him to feel particularly unsafe and ... his extreme psychotic beliefs ... developed," he said.
"He had used drugs before and experienced psychotic thoughts but nothing like this."
Edgerley has pleaded not guilty to murder.
His trial before Justice Soraya Ryan continues.
