Uri Bakay,
I personally am makpid on not talking during davening, and I am bothered by talking, especially during chazaras hashatz, kaddish, and leining. I completely fail to understand why someone would do this, when not only is it a clear cut aveirah, but there is ample opportunity to talk after davening, especially on Shabbos when there is a kiddush. So I sympathize with your feelings on the issue.
That said, it is also a clear cut aveirah to speak lashon hara about the Jewish people, or a Jewish community as a whole. Drawing negative comparisons with other religions, painting all Orthodox Jews with a single brush stroke, and derisively stating “Mi Kaamch (sic) Yisrael” may just be as bad in the eyes of halacha as talking during davening.
I truly understand the frustration that you are feeling, but please don’t let another’s aveirah cause you to commit your own.