Peter Saunders, the head of the Church's taskforce on child protection, said Cardinal George Pell had a "catalogue of denial" on abuse.
The Cardinal, who is the Vatican's finance chief, was making a mockery of abuse allegations, Mr Saunders alleged.
"He has a catalogue of denigrating people, of acting with callousness, cold-heartedness, almost sociopathic I would go as far as to say, this lack of care," he said.
"Given the position of George Pell as a cardinal of the church and a position of huge authority within the Vatican, I think he is a massive, massive thorn in the side of Pope Francis's papacy if he's allowed to remain."
Sue Cox from Survivors Voice, a network of survivors of sexual abuse within the Catholic Church has criticised Mr Saunders' comments, but also remains sceptical over the Vatican's ability to tackle its own legacy of child abuse scandals: "He's [Peter Saunders] made a stupid statement, and I think that's his lack of knowledge and lack of prefessional understanding about what one can say and about what one can't say about a diagnosis of his mental state.
"But the fact remains that the Vatican whipped George Pell away from Australia when the going was getting to much."
On Monday the Vatican also announced that Cardinal Pell will travel to Australia to give evidence more evidence to a state inquiry into institutional responses to child sexual abuse.
"George Pell has avoided this for a long, long time, the Vatican have helped his do that. They are probably making him sacrificial to keep the spotlight away from the Vatican."
Australian-born Cardinal Pell is seeking legal advice after the claims which have been described as "false and misleading".
His spokesperson said in a statement: "Cardinal Pell has never met Mr Saunders, who seems to have formed his strong opinions without ever having spoken to His Eminence.
"In light of all of the available material, including evidence from the Cardinal under oath, there is no excuse for broadcasting incorrect and prejudicial material."
The accusations come during an Australian investigation into historic abuse within the church and state.
The royal commission heard from David Ridsdale who was abused by a priest.
He claimed Cardinal Pell had tried to bribe him in a phone call in 1993, when he told him he had been abused.
"I want to know what it will take to keep you quiet," the clergyman was alleged to have said.
He has denied all of the allegations on several occasions and said he was "horrified" by the claims.
Listen to Sue Cox, Survivors Voice speaking to Premier's Des Busteed: