Rash in Parshas Noach, mishom hefitzom differentiates between dor hamabul and dor hafloga. Dor hamabul was destroyed because of lack of unity but by dor hafloga the unity protected them and they got punished by breaking up the unity. The Sifri says from Ephraim (Hoshea 4,17) that peace protects even from a’z. If there is no unity in a shul, Hashem escapes from there as I and him cannot reside in a one place.
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