'Fall' in the Bible

Therefore, believers, be all the more diligent to make certain about His calling and choosing you [be sure that your behavior reflects and confirms your relationship with God]; for by doing these things [actively developing these virtues], you will never stumble [in your spiritual growth and will live a life that leads others away from sin];

Therefore, [let me warn you] beloved, knowing these things beforehand, be on your guard so that you are not carried away by the error of unprincipled men [who distort doctrine] and fall from your own steadfastness [of mind, knowledge, truth, and faith],