Difficult phrases

[nuni]

Dear All,

Please, help me to understand this sentence, especially the phrases :

When people go off about him bringing in ideological brethren, and saying that he's an ogre, I think that's completely unfair.

Thank you for your help~

[hermit]

When people "go off" about something, they express anger, disgust, impatience,
or some similar negative response.

"Ideological brethren" are associates ("brothers") in a cause or belief, perhaps religious
or political.

hermit