When it broke out on Tuesday evening at Kingston Mosque, neighbouring St Luke's Church allowed worshippers to pray there.
Fr Martin Hislop, who leads St Luke's, then decided to allow the group to keep using a part of the building until their mosque is fixed.
Authorities investigating the cause of the fire do not believe it was suspicious.
He told Premier: "I heard a whole range of fire engines rushing around outside and discovered that the Kingston Mosque, which is between my church and my primary school, had caught light. And so they ended up having three fire engines there, and ambulances and much billowing smoke.
"They were looking for somewhere to do their imminent evening prayer, and so I said I'm sure we could accommodate them in our parish music room and they were very grateful that the offer was made, so that's what I did.
"I take the view... what would our Lord have done? And I remember that it is was in fact the Good Samaritan who our Lord identified as the person who acted justly, not the religious leaders of the day.
"I've not offered the church for use... because that's not appropriate for a Christian building to be used by another faith, but nor would another faith wish to use a consecrated church building.
"My halls on the other hand are there for community use."
Listen to Premier's Aaron James speaking to Fr Martin Hislop:
