The idea that atheism ought be assumed by default is a chimera. Atheism cannot be assumed by default, it must be demonstrated. The belief that given the failure of theistic case for God, atheism ought be assumed does not only commit an appeal to ignorance but is also against the picture painted by modern discoveries in Cognitive Science of Religion (CSR).
Several recent researches in CSR shows that children naturally hold certain universal religious ideas such as belief in divine agents and belief in mind-body dualism. Similar to universals of language, universals of religious belief include principles that are shared in all culture and time, the belief in supernatural beings.