Islam is being “demonised” as a result of atrocities carried out in the name of a “distorted” version of the faith, former Metropolitan Police Commissioner Lord Blair of Boughton said tonight.

The ex-commissioner, who led the Met during the 2005 suicide bombings on London’s transport system, described Islam as one of the “great” Abrahamic faiths and a “faith of peace” which had suffered as a result of atrocities carried out by individuals.

The religious impulse should be recognised as a source of goodness in spite of the “horrors” inflicted by organised religion, he said at the Theos think-tank annual lecture in central London.

Religious people were losing the struggle to make it “clear” that faith impels them to do good deeds, he said.

To most people faith looks “irrelevant, clannish, prejudiced, old-fashioned and violent,” he said.

But the greatest achievements of history, such as the abolition of slavery and the provision of education or free health care for all had their origins in the religious impulse, he said.

”Religion should be the most peaceful of all the agencies of social cohesion,” he said.

”Its infinite number of unseen and unsung acts of charity and love are not known individually but in total they are part of public consciousness.

”They should be and remain the glue that permits modern society to exist, particularly in an increasingly urbanised age - in other words, they are a bulwark of public order, in the sense of orderliness and tranquility.”

In his lecture, Lord Blair, who is an Anglican, emphasised the importance of doubt in religious faith.

He said certainty of being in the right had fuelled religiously-inspired violence.

”Doubt is part of the mortar of a building faith,” he said.

”Unless your faith has been tested by doubt, it is not faith but just an attitude, a retreat from the modern world.

”Doubt in the very nature of faith can surely be a useful companion to a necessary lack of shrill conviction that our own faith is more valuable than that of another.”

He added that, as an Anglican, he did not understand the “obsession” in his own church over women priests and bishops or the way the Anglican Communion was “tearing itself apart” over homosexuality.

He also failed to understand the Catholic Church’s insistence on priestly celibacy, he told his audience.