Bogomils and Cathars were, according to the prevailing theory, "Gnostic dualist heresies" of the Middle Ages. They were Gnostic, because both the Bogomils and the Cathars believed that only the initiated were given the secret knowledge of cosmogony and anthropogony that alone could bring salvation. The first mention of the Bogomils in Bulgaria comes from a hostile source. Bosnia was a country between East and West, Eastern and Western Christian cultures, its position making it vulnerable to the Bogomil teachings. The Cathars used The Vision of Isaiah, an apocryphal Bogomil text; and "of the Gospels they favored the Gospel of John above all others-only it contained the truth". The Cathars in the south of France, according to inquisitorial records, believed that their church was "the true church". The inquisitorial records specify that the Cathars had an ecclesiastical structure: they mention a "bishop", a "deacon", and "an elder son".