It might not be important to you but to me it is fundamental. I was told that by being born again I would be assured of salvation. But when the particular case of the Christian husband who left his wife and kids for another woman came up I wondered if it still applied to him. I thought this Forum would be a good way to help me work things through. But it seems to me that others have as little understanding as I do.
This is not as tough as people make it out to be.
First off, you cannot figure out the salvation of another person for that person. Proverbs 14:10 says,
"The heart knows its own bitterness, And a stranger does not share its joy."
Ephesians makes it clear how we are saved, in chapter 2,
"4 But God, who is rich in mercy, because of His great love with which He loved us, 5 even when we were dead in trespasses, made us alive together with Christ (by grace you have been saved), 6 and raised us up together, and made us sit together in the heavenly places in Christ Jesus, 7 that in the ages to come He might show the exceeding riches of His grace in His kindness toward us in Christ Jesus. 8 For by grace you have been saved through faith, and that not of yourselves; it is the gift of God,9 not of works, lest anyone should boast."
and Colossians 2 tells us how to live this out,
"As ye have therefore received Christ Jesus the Lord, so walk ye in him:Rooted and built up in him, and stablished in the faith, as ye have been taught, abounding therein with thanksgiving."
But you say this person was not always living rooted, grounded, in Him; and in their flesh turned from the truth, and walked as a lost man. This is possible, and happens to believers. But how can this person be assured they are still a believer, how do they know they still retain their salvation?
Well Ephesians 1 says:
13 In whom ye also trusted, after that ye heard the word of truth, the gospel of your salvation: in whom also after that ye believed, ye were sealed with that holy Spirit of promise,
But where's the proof?
Well the Holy Spirit has a few jobs and one of them can be read in 1 John 3:
19 And hereby we know that we are of the truth, and shall assure our hearts before him. 20 For if our heart condemn us, God is greater than our heart, and knoweth all things. 21 Beloved, if our heart condemn us not, then have we confidence toward God.
Further examples for your situation comes out of 1Corinthians, where there was a man who flaunted an affair with his step-mother and Paul told the church in chapter 5 to
"5 deliver such a one to Satan for the destruction of the flesh, that his spirit may be saved in the day of the Lord Jesus."
Paul had stated earlier, he didn't know this man and yet he had already judged him.
3 For I verily, as absent in body, but present in spirit, have judged already, as though I were present, concerning him that hath so done this deed,
We could infer Paul didn't know this man personally, so how did he know he was born again, or how could he know if this man was sincere? Well, I think there are a few interpretations for this. Back in those days, it cost someone to be a Christian! and perhaps just his association with the church tipped Paul off that this man was not fully living out the revelation of his salvation. Or he could have received some very telling information in the letter sent to him prior about this man's conversion, and his testimony was enough to discern his spiritual conversion. Or he could have been given a word of knowledge, a word of discernment. Either way, Paul recognizes his flesh is with Satan, and that his spirit has the ability to retain the salvation he already had, or it could be saved through this turnover. Either way, Paul goes on in 2 Corinthians to give instructions on restoring this man back into the church after he repented.
There is no question regarding "Was he really born again? Are you sure?" It was understood that if this man truly loved God, and desired that relationship, godliness would follow and repentance would be a byproduct.
Jesus said in John 6:
No man can come to me, except the Father who has sent me draw him: and I will raise him up at the last day.
Does your friend desire a relationship with God? Is he repentant of the fact that he hasn't walked after Christ? That doesn't say to me, "This guys really sorry! He's born again!" or "This man needs to get saved!" But by your description it sounds like he's being drawn to Lord and he's being convicted of not believing on Jesus. Something a person walking after the course of this world, doesn't exhibit, nor do they care. The Holy Spirit isn't doing much comforting for the lost, because He's simply trying to bring them out of darkness and into the truth. He's trying to get them to believe on Jesus, and show them how righteousness can only be received as a gift from God.
We go on to read that bringing a person to seeing who they are in Christ, and that desire to live for God is apart of the job of the Holy Spirit in John 16:
7 Nevertheless I tell you the truth; It is expedient for you that I go away: for if I go not away, the Comforter will not come unto you; but if I depart, I will send him unto you. 8 And when he is come, he will reprove the world of sin, and of righteousness, and of judgment: 9 Of sin, because they believe not on me; 10 Of righteousness, because I go to my Father, and ye see me no more; 11 Of judgment, because the prince of this world is judged.
1John 1 says:
8 If we say that we have no sin, we deceive ourselves, and the truth is not in us. 9 If we confess our sins, He is faithful and just to forgive us our sins and to cleanse us from all unrighteousness.
There is an assurance, but if you're looking for a card, or a vision, or something with your name engraved on it, good luck with that. You receive by faith, and it's not something of a human assurance, or a human intuition. It's a God-given intuition that can believe on things not seen. So... Either God's a liar, and he still holding a grudge against your friend, or he's forgiven your friend as His word said, and your friend is simply too carnal to understand that his right standing with God comes through what Jesus did, and not his individual actions.