Former evangelical Steve Chalke has claimed that churches could soon face prosecution over their treatment of LGBT people.
He tweeted over the weekend: "When I began to welcome LGBT people into my church, the Evangelicals threw the charity I founded out of their alliance.
"But I believe what amounts to the abuse of LGBT people by churches is likely to soon see a crop of high-profile prosecutions."
His tweet was in reference to the Evangelical Alliance, which in 2014 discontinued membership of the Oasis Trust, the charity founded by Chalke, after he came out in support of same-sex relationships.
Since announcing his change of view on sexuality, Chalke has become an outspoken advocate for LGBT people.
Chalke made his latest comments ahead of a conference he was hosting on Saturday about creating "safe" churches for LGBT people.
The conference was endorsed by Sir Elton John, who said: "The failure of many churches to welcome, accept and include LGBTQ+ people creates stigma, loneliness, fear and denial, causing lasting damage to their wellbeing and mental health."
Chalke suggested that even offering pastoral concern or prayer could constitute psychological abuse.
"Ultimately every church ought to want to provide sanctuary and safety for all, especially for those who have experienced hurt, rejection or marginalisation," he said.
"While the debate about how to read the Bible in relation to LGBT+ people continues, the absence of safe and affirming churches has had a significant, negative and sometimes tragic impact on LGBT+ people, as well as on their families and friends.
"What churches often describe as pastoral concern, prayer or even 'deliverance ministry' for those with 'same-sex attraction' is, in fact, a highly toxic and psychologically abusive environment where vulnerable LGBT+ people, many of them teenagers or even children, report that they have been taught to believe that their desires are 'sinful'."
In additional comments to the Guardian, Chalke said that the practices of many churches "amount to serious and sustained abuse".
"Churches urgently need to wake up to spiritual, emotional and psychological abuse. If they don't protect young people, the consequences will be massive. This is coming, and it will be a disaster," he said.
Responding to his comments, evangelist David Robertson said that Chalke was wrong to suggest that evangelical churches are not welcoming of LGBT people.
He accused Chalke of trying to "intimidate and bully evangelicals into silence".
"We welcome LGBT in the same way we welcome anyone else – as sinners in need of a Saviour, broken people who need healing, and burdened and weary people who need to know Christ. There are no exceptions and no discrimination," Robertson said.
He continued: "All are called to repentance, faith and conversion to a new life. In Christ we are a new creation. But Steve and his colleagues have a different perspective. They have changed the Gospel. Christ did not come to convert, but to affirm. In this new religion it is sinful to be told that your desires are sinful."
He added: "Steve Chalke was removed from the EA not because he welcomed LGBT people, but because he turned away from the teaching of Christ and taught a false Gospel – which is no Gospel at all."
The Christian Institute's Director Colin Hart raised concerns about the wider implications of a ban on conversion therapy: "Whatever else a conversion therapy law may do, it's clear that LGBT campaigners like Steve Chalke want a veto on Christian preaching, and private prayer and discussion between ministers and members of their congregation."