Last week’s terrorist attack in Manchester has brought renewed prominence to the debate around Britain’s counter-radicalisation strategy, Prevent. A concerted campaign to discredit Prevent has seeped into both elements of the public sector and prevailing thinking on the political left. The success of the ‘Preventing Prevent’ campaign, however, depends on a misunderstanding of the distinction between theology and ideology as well as the radicalising impact of an Islamist ideology, one to which many of the strategy’s most prominent detractors adhere. Understanding the anti-Prevent campaign is one way in which the authorities can more effectively disrupt extremists – a fundamental component of counter-terrorism work.