Discussions between members of a group set up on the WhatsApp service called The Park View Brotherhood also included a description of homosexuals as “animals” with “satanic ways”, the investigation found.
Peter Clarke said in his report that he “came into possession” of a print-out of more than 3,000 postings sent from April 2013 until the group was shut down in March.
The “core contributors” were identified as mainly teachers at either Park View School or other schools within the Park View Educational Trust and all were men.
The report said the group was established by Monzoor Hussain, the acting Principal at Park View, while Razwan Faraz, a former teacher at the school, was allegedly one of the two “most prolific” contributors.
Mr Hussain confirmed that he set up the forum but said the purpose was solely to discuss items that could be included in school assemblies, Mr Clarke said.
The inspector found that the majority of postings were “innocuous and often mundane”.
However, he added: “A number of topics are discussed, often by a small group of contributors, which reveal the members’ attitudes towards education, homosexuality and gay marriage.
“There is also an undercurrent of anti-Western sentiment, explicit antagonism towards the British military, a sceptical reaction to news of terrorist attacks (Lee Rigby and the Boston bombings), and numerous links posted to extremist speakers.”
Some of the messages were linked to conspiracy theory videos about the killing in May last year of Fusilier Rigby and the explosions at the Boston Marathon that killed three people a month earlier.
One post above a YouTube link attributed to poster identified as Teacher L on 24 May last year said: “ATTACK ON ISLAM! Plz watch and share ASAP before they remove it!!!!! London butcher incident; It’s is a hoax And this is the link to reveal it.”
A message sent by Teacher C on 19 April said: “Watch PROOF! Boston Marathon Bombing is Staged Terror Attack on YouTube.”
In May last year Mr Faraz allegedly posted a link to a news article about gay marriage followed by the message: “These animals are going out full force. As teachers we must be aware and counter their satanic ways of influencing young people.”
In September a discussion took place when Teacher A posted a link to an item which described how a shrine in Karachi, Pakistan, is used as a meeting place by gay men.
A message accompanying it said: “IF YOU HAVE JUST EATEN READ AFTER 2 HOURS ... CAUTION ADVISED.”
Two discussions revealed “disparagement” of British armed forces, the report said.
One in May last year was triggered when a group member posted a link to an article about a Birmingham mosque raising funds for the Help for Heroes charity.
Anti-Israeli images showing toilet rolls imprinted with the Israeli flag were also said to have found in the postings.
When interviewed Mr Hussain said he closed down the group because of some of the comments being posted, adding that he “didn’t want to start creating animosity between people”.
Mr Clarke noted that “it is certainly true that Monzoor Hussain challenged some posts”.