By Horav Yosef Yeshaya Braun, member of the Badatz of Crown Heights
Speaking during davening is a very serious transgression for many reasons. Among them are the following:
We may not speak from Baruch She’amar until after the amidah. The tefilah of Baruch She’amar is the opening brachah of Pesukei D’zimra and one may not be mafsik after reciting a brachah. In this case, we may not be mafsik until after Shmoneh Esrei, even for a mitzvah. After Yishtabach one may not be mafsik, even to answer “Amein” (to most berachos).
One should have mora mikdash (awe and fear of the Bais Hamikdash). It is a mitzvah to fear the Aibershter, who is always present in the Beis Hamikdash. This mitzvah also applies to shuls, since they are a mikdash me’at, reminiscent of the Beis Hamikdash.
Hashem says that He is prepared to reveal Himself to Klal Yisrael during the times of davening. If a person talks during davening, they are in essence rebelling against Hashem by demonstrating that speaking to another person is more important to them than speaking to the King of kings.
The only time the Shulchan Aruch uses such strong language as, “Gadol avonam mineso” (Their sin is so great that it cannot be forgiven), is in regard to talking during davening, specifically during chazoras hashatz.
It says in Shulchan Aruch, “Goarim bo” (we should scream at him) – we should strongly rebuke someone who talks during chazoras hashatz. Many stern words are written in sefarim about the terrible sin of talking during davening, such as “Gevald, gevald”(a Yiddish expression of agonized consternation used in Tanya about not davening properly), “Their tefilos are not accepted”, “Speaking during davening causes gezeiros (decrees) against Yidden, chas v’sholom”, etc.
From the negative we can infer the brachos that are conferred upon those who refrain from talking in shul and daven properly. Consequently, it’s crucial for people to get together and make very earnest hachlatos to strengthen the kedushah of our shuls, and to make sure people go to shul to daven, and not to socialize.