In addition, Razum strongly believes and advertises that the Earth is flat.[4]
Razum is also the president of Society for Research of the Threefold Jasenovac Camp ("Društvo za istraživanje trostrukog logora Jasenovac"); he and the secretary of that society popular historianIgor Vukić were both publicly denounced as Holocaust deniers.[5]
In 2018, Razum published a Facebook post expressing support for Richard Williamson, a member of a fringe Catholic breakaway movement who was convicted of Holocaust denial in Germany.[6][7][8][9][10][11]
In January 2019, Razum and Croatian mathematician Josip Pečarić published a book titled Razotkrivena jasenovačka laž ("The Jasenovac Lie Revealed"), which denies that the Ustaše operated an extermination camp at Jasenovac, arguing instead that it was a forced labor camp.[12]