The Church of Christ Pantocrator is usually dated to the late 13th or early 14th century . University of Pennsylvania scholar Robert G. Ousterhout place its construction in the mid @-@ 14th century . Rough Guides author Jonathan Bousfield attribute its building to the rule of Tsar Ivan Alexander of Bulgaria ( r . 1331 – 1371 ) , though during this time control of Nesebar changed many times between the Second Bulgarian Empire and Byzantium . The church is dedicated to Christ Pantocrator , a name of God which hail him as the " Ruler of All " in Greek .