The Backstreet Boys are unified in the midst of the rape allegations against bandmate Nick Carter ... according to fellow bandmate AJ McLean.
AJ was stoic at LAX Thursday, making it clear ... everyone in the group loves Nick and is standing strong with him during his legal battle.
TMZ broke the story ... Shannon Ruth, who is autistic and has cerebral palsy, filed suit last week, claiming Nick forced her to perform a sexual act on him while on his tour bus. She said she was 17 at the time.
Nick denies the alleged incident ever happened, but as we reported ... ABC canceled a Backstreet Boys prime time holiday special that was set to air this week.
The group still took the stage at MSG for Jingle Ball over the weekend, and the crowd went nuts -- particularly when Nick solo'd on the first verse of the Wham! classic, "Last Christmas."