Consider...
See to it that no one fails to obtain the grace of God; that no “root of bitterness” springs up and causes trouble, and by it many become defiled; that no one is sexually immoral or unholy like Esau, who sold his birthright for a single meal. For you know that afterward, when he desired to inherit the blessing, he was rejected, for he found no chance to repent, though he sought it with tears. ( Hebrews 12:15–17 ESV)
Thought experiment:
I'd like to create a thought experiment by briefly describing, or rather, by creating a scenario. I could take several different routes in the creation of this thought experiment, because there have been many versions of this scenario which have played out in many different ways over... well... over the centuries. But I will choose to illustrate a scenario which may be a little bit more typical of our modern context.
Here we go: A man leaves his wife. The reasons aren't as important as one might think. Sure, there are reasons, and I am not saying that reasons are irrelevant, but let's be honest with each other: The vast majority of articulated arguments for doing such a thing will rarely match the underlying reasons which ought to be given when it is done. Regardless, for the purpose of our scenario-painting, this man has left his wife, and the reasons for doing so (whether articulated or not) don't come close, in any stretch of the imagination, to validating that breaking of a covenant before (and with) God.
In the leaving of his wife, this man has also left God. You see, you cannot break covenant with and before God without leaving God. It does not matter what this man may claim, that is what has happened. As the Apostle John says, "Whoever says 'I know him' but does not keep his commandments is a liar, and the truth is not in him." (1 John 2:4 ESV) or James "For as the body apart from the spirit is dead, so also faith apart from works is dead." (James 2:26 ESV) or Jesus, "My sheep hear my voice, and I know them, and they follow me." (John 10:27 ESV) I could go on, but you'd have to be completely oblivious to the Bible to think that you can live whatever life you want, making whatever sinful decisions you want, while simultaneously being cleansed by the blood of Jesus, secure in the hand of the Father, and made alive by the securing work of the Holy Spirit of God. Jesus again, "Truly, truly, I say to you, whoever believes in me will also do the works that I do; and greater works than these will he do, because I am going to the Father." (John 14:12 ESV) And was not the greatest work of Jesus his work of obedience to the Cross? Self-sacrificial, love-motivated obedience to the Father is the work of Christ in us for His glory.
What is this?
So then, what category do we have for this man who walked away? Is our only recourse to state that the regenerative power of the Spirit of God, which brought Christ back from the dead, can be done and undone at the whimsical will of man? That flies in the face of everything we can learn from the Scriptures about what actually happens when one is regenerated -- made alive in Christ -- sealed with the promised Holy Spirit -- brought from death to life -- are true sheep which cannot be plucked from the Father's hand. Surely our wills cannot undo all of that, especially considering that those who have this eternal life are those "who were born, not of blood nor of the will of the flesh nor of the will of man, but of God. (John 1:13 ESV) Truly it must be said that, "...it depends not on human will or exertion, but on God, who has mercy. (Romans 9:16 ESV)
What else do we have? Where do apostates fit in a Theologically accurate universe? Are we left stumped? Are we more stumped because this particular waif may have seemed like a strong and secure Christian at one point? Are we trapped in a Biblical conundrum because it appeared that the Word of God was making an impact in this fella's life? No. Surely not... and in reality not. The Bible is big enough and sturdy enough to handle this situation as well.
Let's start with what we saw in his life by asking ourselves this question: Is there room in God's economy for one to seemingly grow because of God's truth, but not in reality be a regenerated believer because of that same truth? Answer: Yes. Consider the parable of the Sower. You can read this parable in all three of the synoptic gospels (Matthew, Mark, and Luke). If you are not familiar with it, I would highly recommend reading at least one of those accounts before continuing.
I will assume that you've done that or are already familiar with this story. Since that is the case, then most of you know that there are 4 representations of different "soils" (which may be a better name for the parable, "the parable of the soils" might be more accurate). The soils are representations of people and the seed is the word of God, Jesus plainly tells us this in Luke 8:11-15. There are two situations where the word of God (the seed) begins to grow in a person's life (the soil), but it does not last. I would argue that neither of these situations represent genuinely regenerate souls. In fact, I would say one of the main purposes of this parable is to point that out. When people seem to adopt the Word of God, the final assessment on that reality is not in its initial springing up, but in its endurance. Jesus even says that in his Olivet Discourse, "But the one who endures to the end will be saved." (Matthew 24:13 ESV)
Not to stray too far from our nameless dude and his tenuous grasp of a choked out or rootless Word of God in the soil of his heart, but consider taking a deep-dive into the word "saved" in the New Testament. It is rarely used in the past tense, but almost also used in the present and future senses of the word. It is no wonder that Biblical Scholars discuss salvation as past, present, and future when they say, "... we have been saved, we are being saved, and we will be saved."
Back to the scenario:
We've got our man who has left his wife. He now has one and only one directive from God: Repent. This man needs a Nathan the Prophet looking him square in the eye and stating, "You're the man." He must repent of his sin, turn back to God, and seek restoration with his wife. That last part is not irrelevant. The seeking of restoration with his wife is the clearest outward demonstration of his repenting of his sin. There are a lot of what-abouts that want to creep in here, but one could still say that the over-arching command is repent: and a repentance that is demonstrated in a humbly sought-after restoration cannot be ignored. He needs to confess and forsake his sin and any so-called relationships that were a result of that sin. Part of that confession (an agreeing with God) is saying that as well: That was not a loving relationship you found yourself in, that was a relationship based on and rooted in selfishness and God-defying rebelliousness.
I know what you're thinking, "Wait a minute, when did we start talking about another relationship?" You may have had your blinders on, but we were. Whether it was a flesh-and-blood other or just an imagination of another, there is always another.
With that stated, let's introduce the final element of this thought experiment. Let's say that something happens to this guy's wife (or ex-wife). The specific details of the "something happens" is irrelevant for this particular thought experiment. The important part is that whatever it is, the door to a reconciled marriage has closed. Would that reality bear any weight with regard to this scenario?
Think about it. Repentance just got a whole lot (for lack of a better word) easier. At least from the perspective of the spineless wimp that wanted out. I mean, really, that is the one thing he didn't want. He didn't mind all of the other "Christian-y" stuff, but that marriage wasn't suiting him anymore. He was willing to abandon the whole thing, the things he liked and the things he put up with, just to get what he wanted: out. But now... but now there is the opportunity to get those things back that he liked without having to take back the one thing he didn't.
He saw the whole of Christianity, the fellowship of the saints, the church community with all of its friendships... but also he took a look at the redemptive work of Jesus displayed on the cross, the infinite, unconditional Love of the Father to bring about that work of redemption, and the amazingly effective power of the Spirit demonstrating itself in the perfection of a worked out plan of redemption in history, but also in each individual... Our theoretical thought experiment guy took a long, hard look at it all and said, "Yeah, but... I gotta stay married to her."
For it is impossible, in the case of those who have once been enlightened, who have tasted the heavenly gift, and have shared in the Holy Spirit, and have tasted the goodness of the word of God and the powers of the age to come, and then have fallen away, to restore them again to repentance, since they are crucifying once again the Son of God to their own harm and holding him up to contempt. (Hebrews 6:4–6 ESV)
For this guy, that one thing (being free from that marriage) that seemed better than all that God offers has been removed and what is now presented to him is a seemingly easy way back to fellowship and community and eventually (after he can get all the stuff he wants now) heaven. But has it? To be completely honest, I can't help but wonder, as I contemplate the realities of this thought experiment, what may be lost when a death of self is no longer a part of the process. Would the rich young ruler have followed if Jesus had said, "Don't worry about it! You don't really have to sell all that you have!" (See Matthew 19:16-22) Is it not, rather, the very Grace of God when he presents our crosses to us to carry? Is it not his grace when he presents trials that, not only refine our faith, but reveal its presence?
In conclusion, hear the words of the prophet, Isaiah 55:6–7 (ESV)
“Seek the LORD while he may be found;
call upon him while he is near;
let the wicked forsake his way,
and the unrighteous man his thoughts;
let him return to the LORD, that he may have compassion on him,
and to our God, for he will abundantly pardon."
Don't Get Me Wrong!
Please don't misunderstand me. Please. I am not saying that anyone who is currently alive is beyond the opportunity to repent. If you are even thinking about repenting, that is the grace of God in your life. So please: Repent. Do it now. Seriously. Stop reading, get on your knees, and repent. Then get up, thank God that he has changed your mind about your life choices and helped you see them as sin, and go start living for Him.
If I were to offer any clarification here, it would be this: It is abundantly difficult for people to repent when they love other things more than God. That is what Jesus was talking about when he referred to it being more difficult for a camel to enter through the eye of a needle than for a rich man to enter heaven (Luke 18:25). So, here is the remainder of the clarification: If you are only willing to follow Jesus when following Jesus has no person cost, you may not be able to discern whether or not you are following him or following yourself. Discipleship is most clearly seen when there is great personal cost.