I agree with the responders; it's all in a matter of context. (Oh, how I hate that word!)
Personally, I became an atheist after I read the Bible. Don't forget it was Isaac Asimov, the great science fiction writer (and much more) who said: "Properly read, the Bible is the most potent force for atheism ever conceived."
As long as it's treated as literature, it should not be a problem. I would watch it closely and ask him what is said.
My son is a junior and was required to read Job. I saw it as a perfect chance to dissect the bible, pointing out that a petty and human-like god is portrayed playing very horrible games with an innocent human.
So, I would help your brother study and ask him lots of pointed questions. The more people know about the bible, the less they believe.
What parts have been assigned as reading?
I taught the "Bible as Literature" for 30 years in a public school. Everyone knew I was an atheist, so I sometimes had theist parents ask to sit in. I allowed it. I simply treated the bible as I did hamlet. "God" is a character in the bible, as the ghost is a character in "Hamlet."
The book of Esther, by the way, is the plot of most of the Dudley Do-right cartoons, and the story of Samson is "The Honeymooners," The Flintstones," or even "The Cosby Show,' with a tragic twist at the end.The story of King Saul is a tragedy much like greek tragedies--Oedipus Rex, for example.