The population of Flores is predominantly Catholic with a small percentage of Protestants and an even smaller percentage of Muslims, most Muslim communities are centered around the small fishing towns scattered around the coast,  they came as traders many years ago from Sulawesi and eventually settled to make Flores their home.  The people of Flores do not seem to suffer the problems often related with different religions living closely together and have mixed marriages with each religion respecting the next.  You will be warmly welcomed to any of the Church services but don't forget to sing loudly