Although most take it for granted, one of the strangest developments in the history of Christianity is its outright denial of the existence of gods. While many Christians believe absolute monotheism is Biblical, in reality it is a sceptical legacy of the Enlightenment
For the avoidance of misunderstanding, I am speaking here purely of the belief that gods exist (other than the Christian God), and not of any moral evaluation of the gods as good, evil or morally ambivalent. Ancient Jews and early Christians did not deny the gods existed
Absolute monotheism - the idea that not only one deity is worthy of being regarded and worshipped as god, but only one god *exists* - developed very gradually in Christianity
From the start, Christians claimed that the 'gods of the nations' were demons - but the word 'demon' did not yet have the connotations of absolute evil it acquired in the Middle Ages
For an early Christian to say to a pagan 'Your gods are just demons' was to demote the status of the pagan gods to that of daimones, 'small gods' regarded as morally ambivalent beings (a bit like fairies in later folklore). It didn't necessarily imply pagan gods were evil
But as the Neoplatonic theology of daimones receded into the past in a Christian world, demons were seen as progressively more evil (the reasons for this are complex). Medieval Christians remained committed to the idea that pagan idolators were offering sacrifices to demons
And so medieval Christians remained committed to the idea that the gods of the pagans existed (albeit they were evil demons masquerading as gods). So when and how did this change?
At the time of the Reformation, Protestants tended to accuse Catholics of 'vain superstition', and sometimes accused them of being little better than pagans for following empty religious observances
The rhetorical equation of Catholicism with paganism undermined the original Christian critique of paganism as the worship of demons; the idea gradually drifted out of Christian consciousness, squeezed out by intra-Christian polemic
Finally, in the 1690s Balthasar Bekker went the whole way and denied that demons had any capacity to act in the world (including the capacity to deceive pagans into worshipping them), effectively ending centuries of Christian belief in the reality of pagan gods
Later on, some Christians even went so far as to deny that demons existed - although that is a proposition that still remains controversial within contemporary Christianity
To summarise: early Christian monotheism was founded on the denigration of pagan gods - not denial of their existence. In this respect it followed Biblical precedent
What is little understood among Christians today is that outright denial of the existence of pagan gods owes more to Enlightenment critiques of 'superstition' than to Scripture or Christian tradition
Strictly speaking it is a misunderstanding of Christian monotheism to see it as belief that only one God exists; it is rather, belief that only one God is worthy of worship. Church historians must not project a contemporary understanding of monotheism onto the past
And because Christians believed in the existence of other gods until the modern era, they continued to interact with those gods. But that is a whole other issue, far too complex for this thread...
