Büsum's late gothic St. Clemens church, named for Pope Clement I as the patron saint of fishermen, was built between 1434 and 1442. As a relict of Büsum's past as a pirate nest, the St. Clemens church houses a baptismal font and other items raided from the island Pellworm by the pirate Cord Widderich and presented as a consecration gift to the church in Büsum. A carved portrait of Martin Luther from 1564 marks the switch from Catholicism to Protestantism during the late Middle Ages. The altar and lectern date from the early 18th century. Static weaknesses led to a partial loss of the gothic ceiling in 1782, which was replaced by a wooden ceiling.