Universal morality fits better in thr 'God' model, than the 'no God' one. Why would human beings, from all over the globe, throughout history, share a common sense of natural law? If you posit 'Goddidit!', it fits. If you say 'nuthindidit!', why is this universal morality there? Combine that with all the other factors, and atheism becomes just another indoctrinated religious belief.