This paper aims to compare the different strategies used by the colonizers to conceptualize the gods of the vanquished peoples in the interreligious contacts that took place in Hellenistico-Roman Antiquity and in Mesoamerica, from the negation of the alien’s religious system (a feature of extreme barbarism sometimes described in terms of “atheism”) to the more common demonisation of the foreign divinities in terms of idolatry, to the different levels of assimilating them to one’s own religious cosmology through the diverse mechanisms of interpretatio.