January 26. On this date in 1949, Deni MacEoin was born. A former Bahá'í who was active from about 1966 to about 1980, lecturing at Bahá'í conferences and summer schools and writing in support of his religion, he departed after clashes with the Bahá'í administration mostly due to his research works on Babism.

January 26.  On this date in 1949, Deni MacEoin was born.  A former Bahá'í who was active from about 1966 to about 1980, lecturing at Bahá'í conferences and summer schools and writing in support of his religion, he departed after clashes with the Bahá'í administration mostly due to his research works on Babism. He is a pro-Israel activist in Britain who says he has "very negative feelings" about Islam. He writes for The Jerusalem Post and is a Distinguished Senior Fellow at the Gatestone Institute.

From his profile page at The Jerusalem Post...

Denis MacEoin Danis [sic] MacEoin is a former lecturer of Arabic/Islamic Studies, the former editor the Middle East Quarterly, and is currently a Distinguished Senior Fellow at the Gatestone Institute. MacEoin authored several books and reports on Islam, the Middle East, and Israel including 'Dear Gary, Why You're Wrong about Israel', and blog 'A Liberal Defence of Israel.MacEoin is an active supporter of Israel in the UK.

From his profile page at the Gatestone Institute...

Denis MacEoin Distinguished Senior Fellow, Gatestone Institute
Denis MacEoin is a Distinguished Senior Fellow at the Gatestone Institute. He first graduated with a B.A. and an M.A. in English Language and Literature from Trinity College, Dublin, followed by a second 4-year M.A. in Persian, Arabic, and Islamic Studies from Edinburgh and a PhD in Persian/Islamic Studies from Cambridge (King's College).
He has lectured in Arabic and Islamic Studies at Newcastle University, and written several academic books and numerous articles, as well as many pieces of journalism. Recently, he has written reports on hate literature, Shari'a Law, and Islamic schools.
He has worked as a writing tutor as the Royal Literary Fund Fellow at Newcastle University, where he has also taught a short course in creative writing ('Writing in Genre'). He was for some years the editor of a US-based journal, The Middle East Quarterly. In 1992, HarperCollins published a volume of his journalism under the title New Jerusalems: Islam, Religious Fundamentalism, and the Rushdie Affair.

In 2003, Juan Cole described in a message on the Talisman mail list the pressure placed on Denis MacEoin by the Bahá'í Administrative Order...

Denis MacEoin did not withdraw from the faith, he was chased out by powerful Baha'i fundamentalists who were deeply threatened by the implications of his historical work. Denis became a Baha'i in North Ireland around 1965 and quickly emerged as a Baha'i youth leader. He was chosen to come to Haifa to commemorate the 1968 anniversary of Baha'u'llah's Letters to the Kings.
He then wrote the House saying he did not know whether to serve the Faith by becoming an academic scholar of the Middle East or by going pioneering. They wrote back that either path would be praiseworthy. (They later stabbed him in the back about this). He therefore entered graduate school at Edinburgh in Middle East Studies, then went on to Cambridge University for his Ph.D. He was the first academic to study the Babi movement with all the tools of modern scholarship, and his findings were groundbreaking.
Denis made the mistake of continuing to be an active Baha'i. Since the community is so heavily dominated by aggressive fundamentalist fanatics, if a genuine academic wants to be a Baha'i s/he has to keep a low profile. Denis did not. He gave summer school talks. He was once viciously attacked by Abu al-Qasim Faizi. His new ideas were upsetting the conservative British community. He objected when the Baha'i authorities supported dictators like Pinochet and Bokassa. He corresponded with the Los Angeles Study Class and some of his letters were published in their newsletter (a newsletter that the Baha'i authorities later closed down, for all the world like Tehran ayatollahs pulling a publishing license).
Around 1980, fundamentalist UHJ members Ian Semple and David Hoffman called Denis to a meeting and told him he would have to fall silent (rather as the Vatican did to Leonardo Boff). Hoffman was especially harsh. Denis declined to fall silent, and ultimately withdrew from the Faith. He was pushed out by anti-intellectual bigots who had risen high in the Baha'i hierarchy and become Infallible. Denis's works on the Babi and Baha'i movements are some of the few pieces of solid scholarship that exist. Instead of being grateful to him for sacrificing all those years living in penury as a graduate student, studying Arabic and Persian, traveling to a dangerous Middle East, all for the service of Baha'u'llah, the community could think of nothing better to do than viciously attack him and throw him in the gutter of infamy.
Denis's story is the story of most thinking people who have anything serious to do with the Baha'i faith. Either they adopt a cult-like mindset of true believers and covenant breakers, in which case they gradually cease being thinking persons, or they get chased out by the wild-eyed. A few people manage to avoid either fate by not drawing attention to themselves. The Baha'i Extreme Orthodox are like the Borg in Star Trek. They want to assimilate you, but might leave you alone if you stay quiet.
cheers
Juan Cole
https://www.juancole.com/

Juan Cole would continue on subsequent posts...

He wasn't saying anything polemic. He was just discovering who the Babis really were from solid historical sources. The powerful Baha'is, who have all the open-mindedness of Wahhabis, did not like it. It did not look like the fireside talks everyone grew up with, so they shoved Denis out of the community with threats of sanctions echoing about his ears.
cheers Juan

and later

Denis's works were mostly published in Middle East or Religion journals or as academic books, and most could be gotten on interlibrary loan. There may be some things at www.bahai-library.org, and there certainly is a bibliography there.
I apologize that I am off to a conference, so cannot go into depth but there are others here who can discuss Denis's findings.
As to why they should have angered anyone, I suppose you'd have to pass them by a Baha'i fundamentalist and they would tell you. You could just ask about MacEoin at e.g. soc.religion.bahai or about his ideas on Babis. Or at beliefnet. I presume you will get an earful. One of them once more or less threatened to cut my head off with a sword, so they can be an irritable bunch.
cheers Juan https://www.juancole.com/