We have not appointed any one but angels as keepers of Hell , and their number that We have fixed is to make it a means of contention for disbelievers , so that those who were given the Book may be certain , and the faith of the believers may have greater increase , and the people of the Book and believers may not be deceived , and the sceptics and infidels may say : " What does God mean by this parable ? " That is how God leads whosoever He will astray , and guides whosoever He will .