Here are some reasons from what I have seen:1) Some are very harsh.2) There is hypocrisy in one's life while preaching to others.3) Some stop pressing into perfection.4) Some dissimimulate and seek to hide their sin rather than to confess and forsake it.5) Some despise others.6) Sin destroys the faith of some and blinds them to the mercy of God. 7) Some fall away because they slander sincere believers.8) Others depart from the faith of Christ having loved this present evil world and all its vanities.9) Some gradually accept, then crave, then love the praises of men more than the praises of God.10) Others cower to men rather than trembling at God's word.11) They grow weary in well doing.12) Many become offended.13) Some are not studying the bible and learning to rightly divide the word of truth for themselves so they blindly follow another whom they esteem, that has fallen away.14) Some are very cruel to one who has fallen away and have not "considered themselves, seeking to restore such a one in meekness" (Galatians 6).
_________________SI Moderator - Greg Gordon