For this cause I also, when I couldn't stand it any longer, sent that I might know your faith, for fear that by any means the tempter had tempted you, and our labor would have been in vain.
lest by some means the tempter have tempted you, and our labour be in vain: If there were no possibility of the saints being driven into apostasy by the persecution they have endured, then how could Paul’s efforts be "in vain"? Only the prospect of an irremedial abandonment of the faith could have elicited the fear here expressed.