Original sentence: These claims are unsupported (and often vehemently opposed) by mainstream historians.They claim that the intentional mass murder—often in gas chambers—of about 10,000,000 people, including 6,000,000 Jews, and millions of non-Jewish people, including but not limited to Serbs, Poles, Slavs, Roma, Sinti, the disabled, Freemasons, communists, anarchists, homosexuals and Jehovah's Witnesses, is a lie or grossly exaggerated
Edited sentence: These claims are unsupported by mainstream historians.They claim that the intentional mass murder—often in gas chambers—of about 6,000,000 Jews (and millions of others, including but not limited to Serbs, Poles, Slavs, Roma, Sinti, the disabled, Freemasons, communists, anarchists, homosexuals and Jehovah's Witnesses) is a lie or grossly exaggerated