Perhaps the quote below in the 7th century explains the 'gently,gently' approach to taming the heathens..... As christianity had moved into the country through the previous centuries, it followed the old paths of standing stones, barrows, etc. The marriage of convenience was in fact a non-slaughter policy. The devil/demons seen on so many churches was paganism still?

letter from Gregory taken to England by Mellitus;

'When almighty god has brought you to our most reverend brother Bishop Augustine, tell him what I have decided after long deliberation about the English people, namely that the idol temples (fana idolurum) of that race should by no means be destroyed, but the idols in them. Take holy water and sprinkle it in these shrines, build altars and place relics in them. For if the shrines are well built, it is essential that they should be changed from the worship of devils (cultu daemonum) to the service of the true god. When these people see that their shrines are not destroyed they will be able to banish error from their hearts and be more ready to come to the places they are familar with, but now recognizing and worshipping the true god.'

p.s. not an apologist, just an agnostic...