Luke 22
31And the Lord said, Simon, Simon, behold, Satan hath desired to have you, that he may sift you as wheat:
32But I have prayed for thee, that thy faith fail not: and when thou art converted, strengthen thy brethren.
I do understand that the KJV use of "converted" here can be properly translated "to turn back, or to turn to" so I do not think this verse is teaching that it was after Peter turned back that he was "converted" as we say, or born again. It would imply by the word epistrepho, that he had turned to Christ already, then turned away, and would need to turn back.
So I would conclude so far that Peter was converted already. The Son of God prayed for him that his faith would not fail and declared that he would indeed turn back, and when he did, to strengthen his brethren...which he did.
This shows me that Peter's faith never failed. His denial of Christ was a grievous sin, but it was not a denial of who Christ is, but that he himself was not Christ's and that he himself did not know Christ. This he did, no doubt, out of the fear of man.
Yet this must be seen not just of Peter, but of all the disciples because it is written as such and is a fulfillment of prophecy.
"And Jesus saith unto them, All ye shall be offended because of me this night: for it is written, I will smite the shepherd, and the sheep shall be scattered." Mark 14:27 All ye shall be "skandalizō" "to put a stumbling block or impediment in the way, upon which another may trip and fall, metaph. to offend; to entice to sin"
I do not think that bring up Peter's stumbling in fulfillment of prophecy is an argument against the doctrine of repentance as taught either by the LS folks or by the Reformers. Peter and all the apostles stumbled and fell into sin on this occasion and I am sure, on others, just as we do. And some sins a true regenerate person may fall into may be very terrible. So what is the difference then between this and the unregenerate?
The unregenerate falls and does not get back up. The unregenerate does not have the Lord interceding on his behalf that his faith will not fail. This is contained in my confession of faith and reads:
Whereas there is none that doth good and sinneth not, and the best of men may, through the power and deceitfulness of the corruption dwelling in them, with the prevalency of temptation, fall into great sin and provocations; God hath, in the covenant of grace, mercifully provided that believers so sinning and falling be renewed through repentance unto salvation. Ecc. 7:20; Luke 22:31, 32.
RB