I agree with lots of folks here that Bach is great, but I think a real appreciation comes with age. For a teen you might need something more programmatic and/or engaging.
Looking back on my own tastes at that time (and from talking to others) I would suggest 19th- early 20th century Eastern European and Russian composers, starting with Dvorak’s New World Symphony. This is a great period for very engaging music, and it seems like it is very often ignored for “purer” music that kids might find boring. Rachmaninoff, Prokofiev, Shostakovich (maybe a little abstract) all pack a punch. For some really punchy tunes, check out Hindemith, too.
He may not like opera, but that’s just a sliver of vocal music. If you know that he likes classical, look around for Renaissance polyphony (which includes a lot of sacred music). The King’s Singer’s Madrigal History Tour (profane) is a good intro. Others have suggested Tallis, Byrd, Palestrina and Monteverdi. The Hilliard Ensemble has an impressive recording of Tallis’ Lamentations of Jeremiah, a real gem of the period, and of the English couner-reformation as well (a little history lesson you could mix in!).
For something a little more “current,” look for a recording of Handel’s Messiah on period instruments, which also usually means the choir will be smaller and singing in a straighter tone (as opposed to a more bombastic opera style, which is hard to tune and is really hard to listen to, IMHO).
Finally, think of this as an opportunity to educate yourself, as well. There’s a lot of great, inspirational stuff out there. Have fun, and good luck!