Koestler's book was praised by the neo-Nazi magazine The Thunderbolt as "the political bombshell of the century",
[11] and it was enthusiastically supported by followers of the
Christian Identity movement.
[1][13] According to Jeffery Kaplan, The Thirteenth Tribe was "Identity's primary source for the Khazar theory"; they felt Koestler's book confirmed their own beliefs regarding Jews,
[12][14] and sold it "through their
mail order services".
[12]Goldstein writes that "Koestler and the Khazar theory he advanced lives on in the fever swamps of the white nationalist movement".
[15]Michael Barkun writes that Koestler was apparently "either unaware of or oblivious to the use anti-Semites had made of the Khazar theory since its introduction at the turn of the century."
[12]