The Church of England has launched an investigation after a gay man claimed he was subjected to a conversion therapy exorcism in a Sheffield church.

Matthew Drapper, 34, says he was “born into a Christian cult [and] was raised believing Satan is at war with Christians and God is at war with the gays”.

He told the Huddersfield Examiner that he moved to Sheffield from Buxton in 2013, at the age of 25, and joined the Church of England church St Thomas Philadelphia.

Drapper said by that point he had come out as gay, but that he had vowed to remain celibate. In 2014, he claims, the church offered him a chance to “pray that away”.

“I had thought about whether it is even worth living if I’m going to be gay,” he said,

“So, it kind of was a last resort really. By that point, I was like, ‘Well, I’ll try anything.’”

St Thomas Philadelphia has a “belief in the supernatural” and “taught a lot of stuff to do with demons”, Drapper said.

He was invited to a prayer day to “go through our deepest fears”, but this soon became an “exorcism”, he alleged.

Drapper continued: “They told me to speak against the sort of demonic hold that being gay had in my life.

“I was told to renounce the belief system of homosexuality and to cancel my agreement with Satan and to break the power of homosexuality in my life through the blood of Jesus… They told me they could see demons leave my body and go out the window. It was terrifying.”

It took Drapper months to recognise that “something really bad had happened in that space”, and he eventually began accepting his identity.

He was a volunteer at St Thomas Philadelphia at the time, but when he told leaders that he was planning to start dating, he says they said he “wasn’t allowed to work with young adults or children, because I might influence them to become gay”.

The church has denied all of Drapper’s allegations, but finally, eight years on, the Diocese of Sheffield is launching an investigation.

The Diocese of Sheffield said in a statement to the BBC that it believes “conversion therapy is unethical, potentially harmful and has no place in the modern world”, and added that it would keep Drapper informed at all stages of its investigation.

On Friday (4 February), the government’s conversion therapy consultationcomes to an end, hopefully marking a step closer to finally legislating for a ban.

Drapper said: “If conversion therapy had been illegal at the time, then hopefully people would have known enough to intervene and I wouldn’t have gone through that trauma and had eight years of recovering from it.”

St Thomas Philadelphia said in a statement: “St Thomas Philadelphia is a caring and generous church community which does not engage in conversion therapy.

“We welcome the independent investigation initiated by the diocese into these allegations of eight years ago and will participate in it.”

The church has a bizarre and dark history, having been opened in 1998 when it was “planted out” of a huge evangelical church St Thomas Crookes.

According to St Thomas Philadelphia’s website, this planting out was “in response to significant growth and also to a sense of call to the whole city”.

But St Thomas Crookes is also known for being the birthplace of Nine O’Clock Service, often described as a “cult” within the Church of England.

Nine O’Clock Service was an alternative Christian group launched in 1986, which focused on recruiting young people through rock concert-style services featuring lasers in the basement of Sheffield’s Ponds Forge complex.

The group was shut down by the Church of England in 1995 after the group’s leader, Chris Brain, admitted to having sexual contact with more than 20 young female members of Nine O’Clock Service.

A documentary was released chronicling the scandal, and shortly before its release, Brain admitted himself to a psychiatric hospital.