It’s kind of a meme
https://en.wiktionary.org/wiki/my_brother_in_Christ
I heard it with the voice of Macho Man Randy Savage
"Bröther, may I have some öats?"
Kind of, but younger generation will prefix every sentence with "bro" so you can kind of see a generational difference.
But also, Warhammer 40K is popular.
I heard it with the voice of Macho Man Randy Savage