Repentant men of past violence are trying to warn the young

He was imprisoned over the UDA incident, which he carried out at the age of 16, even though the device did not go off.

It is a tragic story of a boy who, Mr McCallum says, felt frustration at being mocked having deaf and dumb parents, who had been sexually abused and who, at a time of violent turmoil, wanted to retaliate for an IRA bomb in his estate.

That one incident Mr McCallum got involved in would have been sufficient to ruin his life, because such convictions have to be disclosed years later when applying for jobs, if he had not radically changed his approach to life and terror.

The authorities were right to jail someone for such an act, even though the fuse on the bomb went out. But while it is necessary for the state to punish and deter such conduct that sad reality does not negate the fact that people who carry out such acts are potentially deserving of sympathy, if they fully recognise their wrongdoing.

That is what Mr McCallum has done, attributing his change of heart to the intervention of God.

His story is a warning to young people against getting involved in violence at the behest of wicked older people. It is particularly pertinent at this time of a dissident republican terrorist threat and ongoing loyalist terrorist criminality.

The ex IRA bomber Shane Paul O’Doherty is among the other people who have shown remorse for their violent past. He wrote: “I ignored the human rights of the people I injured, but I was very touchy about my own human rights. In injuring human beings, I didn’t cure injustices, I created new ones.”

Such testimony is all the more powerful when it comes from people who have once been attracted to terrorism.

The Queen, the Pope and the Archbishop of Canterbury have all warned this season of the dangers of hatred and extremism, and the words of repentant men of youthful violence give weight to their warnings..