All places of worship belong to Allah.....Mosques, Churches, Synagogues, Monasteries etc. So it doesn't matter if one is converted to another...as long as no other name is mentioned besides Allahs.
"And the places of worship are for Allah (alone): So do not invoke anyone beside Allah (in them)." (Qur'an 72:18)
"(They are) those who have been expelled from their homes in defiance of right,- (for no cause) except that they say, "our Lord is Allah". Did not Allah check one set of people by means of another, there would surely have been pulled down monasteries, churches, synagogues, and mosques, in which the name of Allah is commemorated in abundant measure. ..." (Quran 22:40)