When playing "tag" as a child (a.k.a. "tiggy", "chasey", etc.), we also had a "home" base (usually someone's stairs in front of their house) where, if you reached it, you were immune from being "it".

Similarly, Dar al-Islam acts as "home" base for Muslims.  And, just as an embassy is considered part of the sovereign nation of the resident regardless of the hosting country, mosques can also give immunity from being tagged "it".

How many times have we read about police escorting an, uh, Asian youth, who asks to pray?  He goes in, the police wait outside, whoops, where'd he go?  I thought you had him? Oops. "Not it".

"Olly olly oxen free"