A friend of mine has a private group listed on FB and is jailed for 30 days. How is it pos's since everyone in the group has the same views?

After talking to the creator, it comes to the point that anyone that had reposted material from the groups site to the public site would be subjected to the against the tou.

live like a troll, die like a troll

Just because your friend's group is private doesn't make it immune from being put in Facebook jail. All it took was one offensive remark that angered some members, resulting in the 30-day punishment.

Maybe your Friend Said something in the Group that made one of the Members mad and they could have Reported him

Just because the Group Is Private that does not Protect you from Facebook Jail

Views are not themselves necessarily illegal; posting them publicly can be.

He was presumably the one that posted an illegal item, or more hate material or threats of some sort, so got serious complaints.

_Any_ post that breaks the rules on a web site is a criminal offence, but it normally takes quite serious stuff like criminal harassment, promoting criminal acts or making threats to get formal charges rather than just being banned..

[Or he was the creator / organiser of the group, so seen as the one who was overall responsible for its content??]

um, what are you asking?