Originally Posted by
LondonElite
I can't say this with certainty, but I doubt very much that there will be any form of mass at the airport. Depending on your timing, you could exit the airport and go to the catholic cathedrals in either Mainz or Frankfurt. A five hour layover should give you at least an hour in a church, if timings work out for you.
Actually, there is a Catholic chapel which offers mass on Sundays and holidays at 9a.m.:
http://www.kath.de/flughafenseelsorge/gd.html
It is located in T1B departures area (landside)
There also is a Protestant church at FRA:
http://www.seelsorge-flughafen-frankfurt.de/