The Church of England is braced for two years of “deep shame” over its handling of child sex abuse cases, with allegations of cover-ups, collusion and callous treatment of survivors under scrutiny from Monday at the UK’s biggest public inquiry.

The archbishop of Canterbury, Justin Welby, will be cross-examined in person during three weeks of hearings this month. Two former archbishops, serving bishops and other senior church figures are also to give evidence or submit witness statements to the independent inquiry into child sexual abuse (IICSA). Further hearings will follow in July and next year.



Survivors of sexual abuse are expected to accuse the church of failing to act on disclosures and failing to treat them with compassion. Their lawyers are likely to call for independent oversight of the C of E’s safeguarding processes, claiming that the church has shown itself incapable of dealing properly with allegations and disclosures.



Welby himself has said the church must acknowledge where it went wrong. “[We] failed really badly around the issues of the care of children and vulnerable adults. We have to face the consequences of that and learn … to be transparent and honest – and genuinely repentant,” he recently told reporters.



Peter Hancock, the bishop of Bath and Wells and the C of E’s lead bishop on safeguarding, who will also give evidence, told the Guardian he expected to feel “a deep, deep sense of shame” during the hearings.



The church had cooperated fully with the IICSA, but the inquiry would ask “challenging questions and I don’t run from that”, Hancock said. The church needed to learn and that meant “not just new policies, but new courage and resolve” to change.



As well as Welby and Hancock, among those expected to give evidence, either in person or by written statement, are former archbishops of Canterbury Rowan Williams and George Carey, and the current bishop of Chichester, Martin Warner.



In preparation for the hearings, the church has submitted more than 25,000 documents and 36 witness statements.



This month’s hearings will focus on abuse in the diocese of Chichester, where there have been multiple allegations of sexual abuse, some dating back many years. The church’s handling of a controversial abuse allegation made against George Bell, the former bishop of Chichester who died 60 years ago, will be examined. But the issue is far from historical: in 2016, the C of E was dealing with more than 2,600 reports of sexual abuse within its parishes, with more than 700 relating to church officers.



As well as hearing accounts of abuse from survivors, the inquiry is also expect to be told of the “secondary abuse” experienced by many at the hands of church figures who allegedly ignored, disparaged or covered up their disclosures.



“The church is guilty of two distinct crimes: cover-up and its treatment of survivors,” said the Rev Graham Sawyer, a survivor who gave evidence against Peter Ball, the former bishop of Gloucester jailed in October 2015 for sexual abuse. “The corporate narcissism and hubris of the C of E’s leadership has meant they’ve made horrendous mistakes.



“The [IICSA] hearings are going to be immensely uncomfortable for the church, but the key question is whether they will bring about change.”



Gilo, another survivor, said the C of E hierarchy was “likely to go into meltdown” in the coming weeks and months.



“The damage is self-inflicted and centres around denial and dishonesty across the top of the church. The public imagines that cover-up is a thing of the past; I’m not so sure. I suspect we’ll see senior figures in difficulty. There are likely to be resignations. The C of E will need a reboot at the end of all this.”



He hoped the hearings would “shine a spotlight on a broken culture” and usher in a legal requirement to report abuse disclosures to the police. “I do not expect the C of E will look the same in a year’s time. If it does, then IICSA will not have achieved much.”



Richard Scorer, a specialist abuse lawyer at Slater and Gordon, said the hearings were likely to be “highly damaging” for the church.



“They will expose the mistreatment and denigration of victims which happened over many years, and the culture of abuse which was prevalent in the Chichester diocese and the church generally. They will expose the cover-up of abuse allegations, in relation to Peter Ball and many other cases.”



The fundamental problem for the C of E in dealing with abuse was that bishops were not accountable, he said. “A bishop is king in his diocese. If a bishop is resistant to safeguarding there is no real way to overcome this.



“We need external oversight of safeguarding and external handling of complaints, and mandatory reporting of all allegations to police and social services. Until these are put in place the church will continue to have a serious problem. Unfortunately the church is currently unwilling to face up to this reality.”



The church says it has professionalised its safeguarding processes and acknowledges it needs to strengthen its response to survivors. Safeguarding officials see the IICSA hearings as an opportunity to learn from past mistakes with humility and courage.



Alan Wilson, the bishop of Buckingham, who has pressed for cultural change within the church on abuse, said the IICSA hearings would only “examine the tip of a large iceberg”.



He added: “[The inquiry] has promised to go beyond individual failures and the processes by which they were handled and examine habits, attitudes and beliefs that made them so possible and pervasive. An ounce of culture is worth a ton of policy.”