Leaving a shul

Hi,

One should not leave a shul because its members do not act properly; "a little light can dispel much darkness," and his education of others may be effective. However, this does not apply if the shul itself begins to function in a non-halachic manner.

(Rav Moshe Feinstein, Igrot Moshe Orach Chaim 1:99)

Have a great day,
Mordechai