Ouch ... that sounds super painful.
Maybe think of it as a challenge - brush up on your bible and Christian theology. Have a reference handy when you get into bible quoting discussions.
Textual criticism also gives you great ammunition - there is no “original copy” of bible. Many manuscripts with HUGE differences, see the Johnannine coma.
Check out the Old Testament rules and point them out when appropriate
“Did I just see you eat pork sausage”?
“Are you wearing garment made with mixed fibers”!
“It’s Saturday afternoon and you should be observing the sabbath. Are you aware of what the penalty is”?
There are more rules “than seeds in a pomegranate “ and I am sure your roommate is breaking them in dozens...
Who knows - maybe after a few semesters there will be one more atheist in your dorm room.
Good luck :)