When it came to veneration of the cross, Christian authors also appealed to its power. Demons did not tremble before asses, some wrote, but before the cross they shuddered and ran away in fear. (Pseudo-Athanasius, Questiones ad Antiochum Ducem, 623-4) In this way, the cross, in the Christian view, was animated in its own way—it had miraculous power. Hence, there were rational explanations, such as those dependent upon the incarnation, for why Christians venerated the cross in their worship of the one God, but there were also supernatural reasons for the practice as well, for it was through the cross that Christ achieved victory over the devil. In all of this, some attempt was made to explain the practice of cross veneration. At the same time, Christian authors also attempted to mark the distinctions between pagans and Christians. Religious representations may have played a role in both religions, but it was Christian symbols that boasted special and superior powers. (Charles Tieszen, Cross Veneration in the Medieval Islamic World: Christian Identity and Practice Under Muslim Rule [The Early and Medieval Islamic World; London: I. B. Tauris, 2017], 20)
Further Reading:
Answering Fundamentalist Protestants and Roman Catholic/Eastern Orthodox on Images/Icons