Church teaching is fuelling social discrimination against lesbian, gay and bisexual people and driving mental health problems in their community, according to a new report from the Oasis Foundation.

The report, In the Name of Love: The Church, exclusion and LGB mental health issues, says homosexual and bisexual people are up to 12 times more likely to experience mental health difficulties as heterosexual people. It argues this is caused by discrimination against them based on the belief, driven by Christian teaching, that heterosexuality is superior to homosexuality.

According to Oasis, the study demonstrates 'beyond reasonable doubt' that it is churchgoers and Christian leaders who are responsible for negative messages about same-sex relationships in society, the media and political debate.

More than half of LGB young people have self-harmed and 44 per cent have considered suicide, the report says. It cites a study of 27,000 LGB people that concluded: 'Sexual minorities were two to three times more likely to report having a longstanding psychological or emotional problem than their heterosexual counterparts.'

Controversially, the report blames the Church for this. It says every major UK denomination apart from the United Reformed Church discriminates against LGB people and says churchgoers are responsible for the negativity. It points out that at least 74 per cent of the signatories to the campaign against gay marriage, the Coalition for Marriage, were Christians, and at least 54 per cent of the MPs who voted against gay marriage in 2013 were Christians. The report also analysed 100 national media articles on the topic of same-sex marriage and found 47 per cent contained a negative comment; of these, 91 per cent were from a Christian leader or Christian commentator.

The report comes in the wake of a decision by the bishops of the Church of England not to recommend a change in its position regarding same-sex marriage. In his introduction, Oasis founder Rev Steve Chalke praises the bishops' affirmation of the 'worth and dignity' of human beings whatever their sexuality. However, he says: 'I cannot help but conclude that the House of Bishop's report remains yet another missed opportunity to make a positive statement that signals change and therefore, in the end, just one more contribution to the sea of negativity that far too many LGB people are being left to drown in.'

Commenting on the Oasis report, he said: 'It is no secret that the negative stance taken by the Church, and so many individual local churches, has a hugely distressing impact on large numbers of LGB people and leaves countless numbers of them living lives of forced secrecy and dishonesty. Tragically, it is also common knowledge that the resultant anguish and distress often leads to spiritual, mental and physical harm, and in the worst of cases to people making the desperate decision to take their own life.

'Too often however, these powerful testimonies are dismissed by those that don't want to hear them – those who are not yet ready to face up to the scale of the damage that we collectively have unintentionally caused. My hope is that this report is the beginning of a sea change to this approach.'