Leading evangelicals in the Church of England have made one of their strongest stands to date in support of what they say is a biblical view on homosexuality.

A background paper sent out to members of the Evangelical Group on General Synod warns: "The problem with being asked to endorse or make provision for sexual relationships outside of male/ female marriage is that unity is being placed ahead of a shared commitment to biblical truth as we have received it."

The paper cites the examples of Jesus and St Paul: "The never changing vocation of the Church is to be true to the gospel – even if it is counter cultural or at odds with the political philosophy of the time."

It  comes as the synod prepares to meet in York to debate how the Church of England should respond to changing cultural mores on human sexuality. The discussion at York follows two years of "shared conversations" around the country where both sides have exchanged views and experience behind closed doors.

The new paper from the synod evangelical group, known as EGGS, shows that if anything the conversations have led to a hardening of views. 

The paper counters the liberal argument that Scripture can be interpreted in the context of an individual's own experience.

"To hold that Scripture cannot say anything to us that is not simply an echo of our own existing ideas is to refuse to allow God the freedom to educate, challenge and correct us through the texts that he created for that very purpose," it says.

The evangelicals admit that the Church has sometimes been an environment in which same-sex attracted people have felt they needed to hide their sexuality. "This is not healthy and we welcome the greater openness we now have about sexuality. It is also important to note that we are not holding straight married people up as some kind of ideal. Our fallen nature impacts every marriage and all sexuality," they say.

But Scripture sets boundaries so the pursuit of equality does not always mean the church can endorse or bless specific behaviours.

The Church must make decisions based on biblical teaching on marriage and sexual relationships, not secular law, the paper continues.

"The Bible describes all forms of sexual activity outside opposite sex marriage, whether between people of the opposite sex or people of the same sex, as sinful and to be avoided by God's people. There is nowhere in Scripture which suggests any alternative sexual ethic might be legitimate."

Treating everyone with love and respect does not mean the Church giving recognition to beliefs and forms of behaviour that contradict biblical teaching. "To do that would be to disagree with God and this would be the ultimate form of 'bad disagreement'."

It admits that even evangelicals are divided.

"It is the case that a number of (well known) individual evangelicals have changed their convictions regarding sexual ethics in recent years," the group says. "However, the significant issue is not that they have changed their convictions, but whether they have been right to do so. The only way to test this is to compare what they now believe with the teaching of Scripture, and it is our conviction that in order to do so they have departed from a classic approach to Scripture."

They say: "It is because of this that the weight of conviction amongst UK evangelicals is in favour of the Church maintaining its position on human sexuality."

And they reject the argument that conservative teaching on this issue is off-putting to the young.

"It is interesting to note that young people are often inspired by a counter cultural 'call' – and we must not fear to teach a message that is against the flow of contemporary culture."

The issue is significant, the evangelicals say, because sexual sin can exclude a person from being part of the kingdom of heaven. "Whilst this is a challenging truth to receive, it makes it clear that the way we express our sexuality is an issue of fundamental importance."

Simon Sarmiento, of the website Thinking Anglicans, and one of the authors of a new book Amazing Love, that sets out the liberal theological argument for gay relationships, told Christian Today: "The EGGS document is interesting: it recognises that widespread divergences of view now exist among evangelicals and even among EGGS members themselves. But in the end, the argument EGGS seek to sustain rests upon a particular interpretation of the status of Scripture that is, as they themselves acknowledge, not one that is universally held within the Church of England. They would do well to read the account of modern scientific knowledge contained in Amazing Love."