II. Some did backslide.
1. Peter (Matthew 26:69-75). He denied Christ, cursed, lied. One who does these things cannot be a Christian. Luke 22:32 teaches that Peter had a second conversion following his defection: Lu 22:32 But I have prayed for thee, that thy faith fail not: and when thou art converted, strengthen thy brethren.
2. Judas. Judas was given the same power as the other apostles. Had he not been a Christian, this would have been impossible. Judas fell (ceased to be in grace) through transgression. Acts 1:25: That he may take part of this ministry and apostleship, from which Judas by transgression fell, that he might go to his own place.The Bible does not say he was a devil from the beginning. In John 6:70, Judas is called a devil (opposer) just like Peter is called Satan (opposer) in Matthew 16:23.
3. Hymaenaeus and Alexander. I Timothy 1:19-20: Holding faith, and a good conscience; which some having put away concerning faith have made shipwreck: Of whom is Hymenaeus and Alexander; whom I have delivered unto Satan, that they may learn not to blaspheme.
The Bible teaches in II Peter 2:20: "For if after they have escaped the pollutions of the world through the knowledge of the Lord and Saviour Jesus Christ, they are again entangled therein, and overcome, the latter end is worse with them than the beginning." Then verse 21 states: "For it had been better for them not to have known the way of righteousness, than, after they have known it, to turn from the holy commandment delivered unto them."
Also James 5:19-20 "Brethren, if any of you do err from the truth, and one convert him; Let him know, that he which converteth the sinner from the error of his way shall save a soul from death, and shall hide a multitude of sins.