If a Christian struggles with sin is his life and broke a promise he couldn’t keep, is he not part of the family of God anymore? Is it possible to sin to such an extent that there’s no way back home -- basically you lose your salvation? Is there also forgiveness for sins if a backslidden Christian tries to turn around? What about uncontrollable bad thoughts? If you're filled with the Holy Spirit does that mean you're always a child of God?
A broken promise is no different than any other sin. If a person made a promise that he couldn't keep then he should not have offered the promise. That is the warning of James: "Come now, you who say, "Today or tomorrow we will go to such and such a city, spend a year there, buy and sell, and make a profit"; whereas you do not know what will happen tomorrow. For what is your life? It is even a vapor that appears for a little time and then vanishes away. Instead you ought to say, "If the Lord wills, we shall live and do this or that." But now you boast in your arrogance. All such boasting is evil" (James 4:13-16).
While a person remains in his sin, unrepentant regarding the things he has done, then he is lost in his sin (Luke 13:3; Ezekiel 18:21-23). It does not mean that he is no longer a Christian, if he had done what God asked to become a Christian, but being a Christian does not guarantee an entrance into heaven. "And if anyone does not obey our word in this epistle, note that person and do not keep company with him, that he may be ashamed. Yet do not count him as an enemy, but admonish him as a brother" (II Thessalonians 3:14-15). See Will God allow sin to get us back? for additional scriptures.
It is possible to get so wrapped up in sin that a person no longer wants to return. This should not be confused with God refusing to allow a person to come back. See A Sin Leading to Death for more details.
Can a person who stubbornly refused to return to God, or any other sinner, change their mind and return to God? The answer is clearly "yes." "If we say that we have no sin, we deceive ourselves, and the truth is not in us. If we confess our sins, He is faithful and just to forgive us our sins and to cleanse us from all unrighteousness. If we say that we have not sinned, we make Him a liar, and His word is not in us. My little children, these things I write to you, so that you may not sin. And if anyone sins, we have an Advocate with the Father, Jesus Christ the righteous" (I John 1:8-2:1).
But if a person continues to stay in sin and refuses to listen to God's teachings, then there isn't anything I can do to persuade him to return. My only tool is God's word and if that is rejected, then there is nothing left until he changes his mind. "For it is impossible for those who were once enlightened, and have tasted the heavenly gift, and have become partakers of the Holy Spirit, and have tasted the good word of God and the powers of the age to come, if they fall away, to renew them again to repentance, since they crucify again for themselves the Son of God, and put Him to an open shame" (Hebrews 6:4-6). Please note that this passage is written to Christians about trying to get someone who left the faith to come back. It doesn't say it is impossible for them to come back. It is telling the Christian that it is impossible for them to renew the fallen brother if he doesn't want to come back.
So I've been sinning willfully, am I lost? Is there any possibility for someone who's trampled on God's grace to come back? I thought once you were saved it couldn't be taken away? I would like clarification. So many Christians have told me it's not possible to lose it, and I've had a battle on my hands. I've been looking for someone who understands salvation and Heaven. I've always heard that God will never reject a Christian who comes back? I want to hear what you have to say.
If you really thought that salvation was permanent, then why are you asking if it is possible to be lost? If God doesn't reject a Christian who comes back, then what about the Christian who doesn't come back? What I'm trying to do is point out the inconsistency behind your questions.
If a Christian cannot fall, then why are there so many warnings, such as "Therefore let him who thinks he stands take heed lest he fall" (I Corinthians 10:12)? Why are there warnings to be on guard against sin, such as "Be sober, be vigilant; because your adversary the devil walks about like a roaring lion, seeking whom he may devour" (I Peter 5:8)? If a Christian cannot sin to the point of being lost, then these warnings are meaningless. See Cannot Sin and Is "Once Saved -- Always Saved?" a Bible Doctrine?
But things that are lost can be found again. That is the point of the parable of the Prodigal Son. "For this my son was dead and is alive again; he was lost and is found" (Luke 15:24). In writing to Christians, John said:
"If we say that we have no sin, we deceive ourselves, and the truth is not in us. If we confess our sins, He is faithful and just to forgive us our sins and to cleanse us from all unrighteousness. If we say that we have not sinned, we make Him a liar, and His word is not in us. My little children, these things I write to you, so that you may not sin. And if anyone sins, we have an Advocate with the Father, Jesus Christ the righteous" (I John 1:8-2:1).
The problem is that not everyone who sins is willing to return. "This charge I commit to you, son Timothy, according to the prophecies previously made concerning you, that by them you may wage the good warfare, having faith and a good conscience, which some having rejected, concerning the faith have suffered shipwreck, of whom are Hymenaeus and Alexander, whom I delivered to Satan that they may learn not to blaspheme" (I Timothy 1:18-20).
The warning in Hebrews 6:4-6 is written to Christians who have remained faithful about the problem of dealing with fallen Christians. When a Christian falls due to weakness, I can encourage him and teach him using the word of God. But when a Christian purposely reject Christianity and the Bible, I have nothing to use to help him. It is impossible for the faithful Christian to make the willfully sinning Christian to come back. Notice in the parable of the Prodigal Son again. When the younger son wanted to leave, the father did not stop him -- in truth, he would not be able to stop him. He didn't chase after the son because it would have made no difference. But the son chose to come back and that made all the difference in the world. Even the worse, most calloused sinner can come back if he wants too. The faithful Christian's hands are tied until the sinning Christian decides to return.
What happens to a Christian who dies without returning to God? The answer is the same in regards to the sinner who never comes to Christ in the first place. "But when a righteous man turns away from his righteousness and commits iniquity, and does according to all the abominations that the wicked man does, shall he live? All the righteousness which he has done shall not be remembered; because of the unfaithfulness of which he is guilty and the sin which he has committed, because of them he shall die" (Ezekiel 18:24). God looks at who you are, not who you were, when it comes to salvation.
I'm confused about this statement: being a Christian doesn't guarantee you an entrance to heaven? Are you talking about someone who professes of being a Christian who actually isn't, or someone who's a born again Christian filled with the Holy spirit?
Both. Jesus said, "Be faithful until death, and I will give you the crown of life" (Revelations 2:10). So what happens if you don't remain faithful? "Therefore, since a promise remains of entering His rest, let us fear lest any of you seem to have come short of it. ... Let us therefore be diligent to enter that rest, lest anyone fall according to the same example of disobedience" (Hebrews 4:1, 11).
"Beware, brethren, lest there be in any of you an evil heart of unbelief in departing from the living God; but exhort one another daily, while it is called "Today," lest any of you be hardened through the deceitfulness of sin. For we have become partakers of Christ if we hold the beginning of our confidence steadfast to the end" (Hebrews 3:12-14).
You can't depart from something you never had.