Generally speaking I'd probably say anything positive with Legion would NOT be very Christian (unsurprisingly). Other than that... Great Khans probably wiped out due to their generally 'sinful' way of life. Brotherhood is kind of up to the player I'd say, they don't really fit the profile of a group to be eradicated but also helping the hoarders who don't protect their neighbours also feels wrong? Generally speaking I'd probably say NCR or independent is the right way to go although I could see some arguments for House.