وَإِذَا قَرَأْتَ الْقُرْآنَ جَعَلْنَا بَيْنَكَ وَبَيْنَ الَّذِينَ لَا يُؤْمِنُونَ بِالْآخِرَةِ حِجَابًا مَّسْتُورًا 
if people knew Allah pretty well, they would obey Him and seek to attain the Good pleasure of Him, but the demons of mankind and the jinn do everything in its power keeping people away from knowing Almighty Allah the creator.