427 (selections IV).

There is no surer sign of extreme weakness than the failure to recognize the unhappy state of a man without God; there is no surer sign of an evil heart than failure to desire that the eternal promises be true; nothing is more cowardly than to brazen it out with God. Let them then leave such impiety to those ill-bred enough to be really capable of it; let them at least be decent people if they cannot be Christians; let them, in short, acknowledge that there are only two classes of persons who can be called reasonable: those who serve God with all their heart because they know him and those who seek him with all their heart because they do not know him.