See the thing is, I believe that probably the only way to get a decent person to do bad things is through religion, or some other dogmatic methodology, where that person believes such a system without question. Sure , normally good people do good things and some bad things, bad people to bad things and some good things (Hitler wasn't hurting anyone when he brushed his teeth) but in order to get a genuinely good person to do morally questionable acts, you needs something, like a dogmatic constant, to get them to do it.
Perhaps we differ on the definition of a "genuinely good person" as I think your definition is overly simplistic. But Stanley Milgram proved conclusively sixty years ago that the only thing it takes to make a good person do a bad thing is an authority figure ORDERING him to. Authoritarian religions have this feature because, obviously, they have ALOT of authority figures. But authoritarian governments, organizations and societies have the exact same problem. If you're in a secular military in a secular country and your commanding officer orders you to go into a house and kill everyone in it, it doesn't matter how "good" you are, you're indoctrinated into a culture of command and authority in a military system and you're going to do it regardless.
it has been demonstrated that religion is inherently divisive and does cause harm,
Again, the same feature is present in authoritarian structures. There are certain people who have a natural predisposition to zealously preserve and defend higher authority figures, whoever those might be. This goes way beyond simply being a tool, there are actually people in this world who rabidly and pathologically side with the overdog in every single case. These people are usually fanatics just waiting to be recruited, doesn't matter by whom; if the secular humanists decided to wipe out anyone who ever worshiped a deity, they would sign up in a heartbeat.