When historian Tom Holland’s documentary, Islam: The Untold Story, originally aired on Channel 4 in late August, it prompted over 1,000 complaints to the network and 200 to regulator Ofcom. Now, the UK broadcaster has cancelled an invite-only screening that was to be held this Thursday at its London headquarters, saying it did so after “having taken security advice.” Among the Twitter messages Holland has received since the broadcast is one that reads, “You might be a target in the streets. You may recruit some bodyguards, for your own safety.”

The controversial doc examines the origins of Islam and questions some of the writings in the Koran. In the film, Holland says, “When it comes to Islam’s beginnings, there is no full light of history… I felt like I was being sucked into a black hole.” After the Aug. 28 airing, the Islamic Education and Research Academy responded, saying in part, “Holland appears to have turned a blind eye to the rich Islamic historical tradition. There are no ‘black holes’ and there is no missing information.”

In a post to Channel 4’s website, Holland contends, “This film is wholly in keeping with other series and programs on Channel 4 where the historical context of world religions has been examined,” such as his own The Bible: A History. Today, the broadcaster provided Deadline with the following statement: “Having taken security advice, we have reluctantly cancelled a planned screening of the program Islam: The Untold Story. We remain extremely proud of the film which is still available to view on (on-demand service) 4oD.”