A bill aimed at banning gay-to-straight conversion therapy has been denounced by the social conservative Christian group Anglican Mainstream as a “threat” to Christians.

In December, Labour MP Geraint Davies published a Private Members’ Bill in Parliament aimed at banning gay-to-straight conversion therapy by regulating the psychotherapy sector.

If passed into law, the Counsellors and Psychotherapists (Regulation) Bill would require all therapists to register with a government-approved body.

The bill will receive its second reading on 24 January.

Christian Concern, the evangelical organisation founded by Andrea Minichiello Williams in 2008 to protect “Britain’s Judeo-Christian values”, is also opposed to Mr Davies’ proposal.

Writing on the Christian Concern website, Anglican Mainstream Executive Secretary Reverend Andrew Symes said: “According to the Bible, God is in the ‘conversion’ business. Christian faith is not an emotional or intellectual construction, something we create or imagine, but a response to God who reaches out to rebels, calls them to turn around and enter into a restored relationship with him. God wants all of us to repent, to be transformed, to be born again.”

Urging gay people to “overcome” homosexual practices, Rev Symes went on to say: “It has also been generally agreed that stable, loving, heterosexual marriage is a foundational cornerstone for a stable society, and that this necessarily involves encouraging people to overcome natural tendencies to promiscuity, adultery and homosexual practice. Only recently, in the last few years, have these axioms been challenged.”

Defending the discredited medical practice of gay-to-straight conversion therapy in reference to Mr Davies’ bill, Rev Symes said: “This bill is a threat to Christian counsellors who work in this area, and to people with same-sex attraction who want to access counselling that is trained and accredited. Currently anyone with same-sex attraction has freedom of choice to do one of three things: to embrace ‘gay’ identity and enter into a homosexual relationship or relationships; to live with the feelings but resist the temptation to act on them and live a life of celibacy, or to seek to reduce the feelings and develop heterosexual attraction, perhaps with a view to marriage and family.”

He added: “The bill seeks to deny the latter of the three choices, thus creating a major and completely unnecessary restriction on human liberty. It is also a threat to religious freedom: the right for a person not just to believe in Christ, but to seek help in following him in every area of life.

“It is a threat to church autonomy: the bill seeks to give the government control over what Christians may believe and teach about sexual ethics, because it would set into law the idea that to attempt to change sexual orientation is ‘harmful’. But even more seriously, it seeks to take away from God the right to bring change in a particular area of human life. It is directly contradicting God’s word.”

In November, the UK Government resisted calls by MPs to introduce statutory regulation of psychotherapists in order to prevent them from being able to carry out gay-to-straight conversion therapy.

Health Minister Norman Lamb said it was “utterly abhorrent” but that the Department of Health was not aware of cases of it being prescribed on the NHS.

Lesley Pilkington, the Christian psychotherapist who was found to be providing the therapy, was struck off by the British Association for Counselling and Psychotherapy (BACP) in September 2012.