In a speech to the Secondary Leaders' Conference of the Catholic Association of Teachers, the Archbishop of Westminster will stress the need to spot the signs of radicalisation early.
Cardinal Nichols has been meeting people involved in the prevention of extremism.
According to a speech seen by the Catholic Herald he will say: "One said that it was clearly possible to bring a person to the point of being willing to leave all for the sake of their newfound cause, even to the point of embracing violence or suicide, within a four- or five-week period.
"One month is all it takes to transform a dissatisfied and disorientated teenager into a terrorist.
"We are talking about the age of children in your schools, in your care. We are talking about youngsters around here."
He'll warn a mix of naivety, isolation, loss of shared values and easy access to the internet are making it increasingly easier for Islamic State to turn teenagers to their cause.
"It is to teenagers such as these that the call of a definitive, demanding faith, one which asks for a heroic sacrifice in a wide cause for victory ... is cast as a true fulfilment of all the unfocused yearning within them," he'll say.
He'll urge Catholic teachers to come up with a Christian purpose that has the same pull as Islamic State.
