There are several words for church in Czech - 'katedrála', of course, and 'chrám', which mean practically the same thing, then 'kostel' (church), and 'kaple' (chapel). These all refer to actual buildings. But this protestant church is called 'sbor', which really means congregation. The word was used to indicate the significance of the people themselves to John Hus and his followers. They were utraquists, who argued that the congregation, not only the priests, should be allowed to receive the body and the blood of Christ (utraque means 'in both kinds' in Latin). For this reason, their symbol, of a chalice, appears on top of Hussite churches, as well as the cross.
The Hussite movement flourished at the end of the 14th and start of the 15th centuries, and their fierce conviction led to many bloody wars against the Catholics. Hus was eventually tried and burnt at the stake, but his writings crucially informed the arguments of Martin Luther in the following century.
Hus, whose name by the way means 'Goose', was also responsible for introducing an important feature of the Czech written language, the diacritical mark - ˇ - the so-called 'háček' (hooklet) which appears over certain consonants and the vowel 'e'. Over 'c' and an 's' it has the same effect as adding an 'h' in English - in other words it makes the sounds 'ch' and 'sh'. Adding it over an 'e' or an 'n' makes a 'yeah' or 'nyuh' sound. And adding it over an 'r' is something you should not try to do unless you have had a few drinks.