There was a time when Church leaders wrote letters that proclaimed and affirmed the Christian faith, challenged false gospels and glorified Christ. Think of Paul's letters in the Bible or the wonderful letters of John Newton or JRR Tolkien. They are edifying, exhorting and encouraging.

This week a letter was sent from some professed Christian leaders in the UK which is directly the opposite. The Rev Canon Steve Chalke, Rt Hon Dr Rowan Williams, former Archbishop of Canterbury; Very Rev Rogers Govender, Dean of Manchester Cathedral; Professor Susannah Cornwall, Professor of Constructive Theologies, University of Essex; Rev Paul Bailey, Pentecostal Minister; Very Revd. Dr David Ison, Dean of St Paul's Cathedral; and several other suitably entitled church leaders.

In their letter to the Prime Minister, they lament that the government's ban on conversion therapy excludes trans people, and it is worth examining both the background and detail of this letter.

The government itself has got into a bit of trouble over this issue. Firstly, it was announced that it was going to backtrack on the ban on so-called conversion therapy and instead use the existing laws to deal with any wrong practices.

But within 24 hours of this U-turn, the government did another one and said it was going ahead with the ban – except for trans people. This U-turn was largely the result of pressure from Tory MPs who haven't really thought the issue through and didn't want to be seen as the 'nasty' Tories again. Of course, the political and media elites could hardly contain their outrage – cue Twitter 'outrage' and lots of stories and reports – and so the U-turn was itself U-turned.

But the latest U-turn was not enough for these Christian leaders; they want the government to go much further. And what their letter reveals is that they are a million miles away from the New Testament letters and the teaching of Jesus. In my view, there are three basic errors which remove them from Christ's teaching.

1. They do not understand what 'conversion' is. Or indeed what a Christian is. The letter argues that "conversion to Christianity is the event or process by which a person responds joyfully to the glorious embrace of the eternally loving and ever merciful God".

They go on to say, "To be trans is to enter a sacred journey of becoming whole, precious, honoured and loved, by yourself, by others and by God."

This is a classic example of people using spiritual language which sounds good, in order to undermine and change what Jesus actually said. Jesus did not come to call the righteous, but sinners to repentance (Luke 5:32). He urges us to "produce fruit in keeping with repentance" (Matthew 3:8). He tells his church, "Those whom I love I rebuke and discipline" (Revelation 3:19).

There are hundreds of similar verses throughout the Bible which show clearly that the Good News is not 'God accepts you are you are and wants to affirm you', but rather that because God loves you, He wants to change what you are, heal you, forgive you, and give you a new heart.

This is radical conversion. The conversion described by the letter's signatories is little more than a meaningless meme – with no substance, no love, no reality and no forgiveness. It is in a different spiritual universe from what Paul wrote to the Colossian church: "Put to death, therefore, whatever belongs to your earthly nature: sexual immorality, impurity, lust, evil desires and greed, which is idolatry" Colossians 3:5.

Rather than heal and make whole, these signatories want to put sticky tape on the wound and pretend that people are already whole. But the gospel of self-love is not good news.

2. They are closed-minded, intolerant and exclusive. The letter argues that so-called conversion therapy is "pressure put by one person on another to fit their expectations". Never having experienced conversion therapy, or met anyone who has, I cannot comment on that. However, I do recognise coercion when I see it. Like when, for example, Steve Chalke encouraged the government to prosecute evangelical churches for teaching 'harmful' doctrine. These clergy, like Saul heading for Damascus, are determined to put pressure on those who do not fit their expectation or accept their ideology.

There is no question that this anti-conversion therapy bill is aimed at evangelicals and Catholics. The Independent newspaper, for example, had no doubt who was to blame for the U-turn. It cited a "Tory source" as saying: "But the problem is he (the PM) is surrounded by nutty evangelical advisers who think that their religious views are more important than what's right for the country."

Apart from the arrogance of this Tory insider assuming that he knows what's right for the country, what struck me about this was the mocking language. I wonder if any other religious group would be spoken about in such a derogatory manner?

This bill is not designed to stop coercive practices which are already illegal; it is aimed at imposing the progressive anti-Christian ideology of these clerics onto all of us. The State theological thought police are coming - and this is the UK, not Saudi Arabia.

3. They do not grasp what the church is. Or indeed prayer.According to this new religion, any prayer that does not affirm what a person truly is, is apparently manipulative and coercing. So, Jesus got it wrong when he said that we should pray "forgive us our sins"? Or that we should ask for a clean heart and a new spirit? And clearly he was being manipulative and coercing when he declared that unless someone underwent such a a radical change as the new birth, they would not even see the Kingdom of God (John 3).

The clerics behind this letter repeat their one-point sermon for the Prime Minister: "Every church should be a safe space that affirms people in who they are, without fear of judgement."

You don't need a degree in theology to work out that this is not the New Testament church. If you read the New Testament, you will find that there is considerable judgement within the church. I just wonder how 'safe' Ananias and Sapphira felt?! (Acts 5).

Was Paul encouraging safety when he told the church to judge those within, rather than without? (1 Corinthians 5:12). Maybe Jesus was a little over the top when he warned about wolves among the sheep (Matthew 7:15)? Perhaps he was being ironic and really meant to say to the wolves, 'we welcome and affirm you as you are. The fact that you are a wolf is just your nature; come in amongst the sheep'!

Again, the trouble with the words used by the clerics is that, at a superficial level, they sound nice. Of course we want safety and non-judgementalism but on examination, not only are the words in this letter meaningless and contrary to the teaching of Christ; they cause harm. While attempting to create a 'safe space' for some, they are making the world distinctly more harmful for others. In promoting transgender ideology, they are harming women, children and indeed, men.

Take for example the incredible story of the brave Scots woman, Sinead Watson. It is astounding that doctors are being incentivised in Suffolk with £178 per year for every adult they prescribe cross-sex hormone therapy. Surely it is this kind of 'conversion therapy' that should be banned?

One doctor involved in transgender surgery told me that there was an 80 per cent negative outcome - an unheard-of figure for a medical procedure. Yet this doctor cannot speak out, such is the pressure put on them by the ideologues.

Sinead's story can be repeated thousands of times. Which is why JK Rowling, Kathleen Stock, Abigail Shrier and others are fighting for women – at great personal cost. I recall one teenage girl who came to see me after detransitioning and telling me of the pressure she came under to transition in the first place - and of the horrific abuse and threats she received when she detransitioned.

The letter from the clerics reminded me of the letters from the religious leaders in Jerusalem that Paul obtained, giving him permission to persecute the Christians in Damascus (Acts 9:1-2).

The signatories to the letter appear determined to root out what they perceive as anti-trans heresy, and they write to the authorities seeking permission to do so.

The one hope I have is that Paul was converted on the road to persecute the Christians in Damascus. I pray that those who would teach anti-Christian and indeed anti-human doctrines that would cause so much harm – and do so in the name of God - would have that same conversion experience. It's not therapy. It's revolutionary!

David Robertson runs The ASK Project in Sydney, Australia. He blogs at the Wee Flea.