In a large balcony above the beautiful main hall at Regent's Park Mosque in London - widely considered the most important mosque in Britain - I am filming undercover as the woman preacher gives her talk.
What should be done to a Muslim who converts to another faith? "We kill him," she says, "kill him, kill, kill…You have to kill him, you understand?"
Adulterers, she says, are to be stoned to death - and as for homosexuals, and women who "make themselves like a man, a woman like a man ... the punishment is kill, kill them, throw them from the highest place".
These punishments, the preacher says, are to be implemented in a future Islamic state. "This is not to tell you to start killing people," she continues. "There must be a Muslim leader, when the Muslim army becomes stronger, when Islam has grown enough."
The mosque is meant to promote moderation and integration. But although the circle does preach against terrorism and does not incite Muslims to break British laws, it teaches Muslims to "keep away" and segregate themselves from disbelievers: "Islam is keeping away from disbelief and from the disbelievers, the people who disbelieve."
Friendship with non-Muslims is discouraged because "loyalty is only to the Muslim, not to the kaffir [disbeliever]".
To be fair and, indeed, complimentary to Sunny Hundal for a moment—shock, horror!—this sort of intolerance is something that he and his colleagues at Pickled Politics have made a specialty out of skewering.
It is the segregation aspect that I find particularly worrying: creating a self-selecting group of people, preaching evil things to them and then ensuring that they not only see themselves as different (and superior) and but also have little interaction with anyone else in society can only lead to tears. And explosions.
All religion is stupid: you only have one life and it is up to you to live it decently. And stoning and mutilating people is not the way to do that.