It's often interesting to explore differing beliefs. An outing to St. Julian Basilica is a good way to appreciate one of the local religions and cultures.
You'll have sightseeing choices galore when in Brioude. St. Julian Basilica is a great place to start here, but there are many other fine spots to discover. Lace Museum, Sources and Gorges of Allier Trail, and Aquarium of Brioude are near the house of prayer and and will cap off your day nicely.