The Archbishop of Canterbury is warning the Church of England against 'radical change' as it struggles to deal with the challenges of dwindling numbers and clergy sex abuse.

Justin Welby cautioned against a 'throw the baby out with the bath water' approach that he said would lead to disaster and a 'bunker mentality'. He said that while the church must adapt, it 'cannot be done quickly'.

'To call for radical change without being aware of the traditions that underpin and secure the structures to which we belong is likely to lead to disaster, typically through division. It stirs fear rather than hope, and encourages a bunker mentality rather than a willingness to see transformation,' he told the church's ruling general synod.

But he also warned that the church must 're-earn our existence in each generation' as the established church.

'That means change,' he said adding that 'will demand immense sacrifice' from both deeply entrenched traditionalists and liberals. 'It requires our willingness to be more concerned about opening our doors and throwing down barriers and boundaries, than protecting our frontiers and keeping the enemies out,' said Welby.

'But the questioning of ourselves, our attitudes and structures, must be in love, and faithful to the faith uniquely revealed in the Holy Scriptures and set forth in the catholic creeds, which faith the church is called upon to proclaim afresh in each generation.'

He added: 'One mistake is to imagine we can change everything and the other mistake is to believe we should change nothing.' 

Welby's words will dismay those hoping for rapid change in the church's teaching on marriage and sexuality. He reminded members of synod that links with the rest of the global Anglican Communion, 90 per cent of who come from the largely conservative global south, are more developed thanks to easier communication.

'That means that the questions of change are ever more complex, unless we reject our catholicity and the very concept of the church as universal,' he said. 

Throughout his address Welby walked a tight-rope between calling for change while defending its slow pace within the church. 'Scripture, and our history and our tradition remain key parts of our thinking, along with reason' when thinking about progress, he said.

As well as sexuality, the church is facing a number of challenging issues primarily around its approach to allegations of clergy sex abuse. Peter Hancock, the lead bishop of safeguarding, revealed the CofE dealt with around 3,300 cases of abuse in 2016 alone, roughly 594 (18 per cent) of which were made against church leaders.

Welby called for a 'culture change' in the approach to safeguarding.

Members of the general synod, which acts as the church's parliament, will hear a presentation on safeguarding on Saturday morning. Survivors of abuse will protest outside during the presentation, which many say should be a debate, and the Archbishop of York will join them for a two-minute silence beforehand.