Sichah bateilah b'beit haknesset
Not Talking in Shul
Who defines Jewish ways - what Jews do, or what the books say that Jews should do? Around no issue is the gulf between these two greater than over question of talking in shul. This has been a battleground between rabbis and regular Jews for centuries. As much as rabbis inveigh against speaking in synagogue, Jews do. We are talkative people.
On the side of the books, the halachically authoritative Shulchan Aruch is perfectly clear on this subject. The author, Rabbi Yosef Caro, stated: "One may not behave frivolously in synagogues, for example by indulging in idle, empty conversations."
The Mishnah Berurah in his commentary weighs in with what must have originated as a barnstorming sermon against talking in shul. He writes that this prohibition even includes regular business talk which would be fine outside a shul. But as for gossip, slander, quarrelling and machloket [argument], these are serious sins at any time but are incalculably worse when committed in shul where they demonstrate contempt for the Divine Presence that dwells there. And sometimes what begins as a private argument spreads until it engulfs everyone and the whole shul becomes like a blazing bonfire...