Space impact “saved” Christianity?

BBC News Story
An interesting hypothesis, that the celestial event that the Roman Emperor Constantine saw in AD 312 that swayed him to a conversion to Christianity was really a large meteorite impact…and a group of scientists think they have found the crater.
Constantine’s conflict with Maxentius is not a new idea for a turning point. I remember reading, years ago, a alternate history story set several hundred years after Constantine loses the battle at Milvian…and thus the knowledge of the Roman Empire is lost, its glory in complete ruin as there are no Christian monks to keep the knowledge alive and growing in this dark alternate world.