Listening to the guys mental health problems, the whole incident sounds very similar to someone I knew.
He had similar mental health issues, smoked a lot cannabis, stopped socialising. People got concerned and called the doctor, but it was too late, and he killed someone. After he was arrested, he claimed he was doing “God’s work” and got called a religious fanatic in the press (he’d never previously been particularly religious but his parents attended church).
I think pyschosis causes religous delusions, and presumably the religion is one the sufferer is familiar with.
He was taken to a secure mental hospital for around 11 years, until he was deemed fit enough to stand trial, where he was convicted of murder and sent to Jail.
It wasn’t labelled terrorism.