ALL sin (except rejecting Christ until you die) is forgivable. However one MUST REPENT of sin and turn to God through faith in Christ. without repentance, there is no forgiveness.
Acts 26:20 but kept declaring both to those of Damascus first, and also at Jerusalem and then throughout all the region of Judea, and even to the Gentiles, that they should repent and turn to God, performing deeds appropriate to repentance.
Acts 8:22 Therefore repent of this wickedness of yours, and pray the Lord that, if possible, the intention of your heart may be forgiven you.
Christ is the one God gave to grant repentance and forgiveness.
Acts 5:31 He is the one whom God exalted to His right hand as a Prince and a Savior, to grant repentance to Israel, and forgiveness of sins.
If we believe, we receive forgiveness of sins.
Acts 10:43 Of Him all the prophets bear witness that through His name everyone who believes in Him receives forgiveness of sins.
But belief MEANS obedience to Christ (ie, stop sinning).
John 3:36 He who believes in the Son has eternal life; but he who does not obey the Son will not see life, but the wrath of God abides on him.
If we believe, we will confess our sins and be forgiven.
1 John 1:9 If we confess our sins, He is faithful and righteous to forgive us our sins and to cleanse us from all unrighteousness.
But if you do not have the belief, which leads to obedience, then you have the wrath of God still upon you regardless of what you say or do.
John 3:18 He who believes in Him is not judged; he who does not believe has been judged already, because he has not believed in the name of the only begotten Son of God.
And people in those situations will be judged and enter the lake of fire.
1 Corinthians 6:9-10 (NASB)
9 Or do you not know that the unrighteous will not inherit the kingdom of God? Do not be deceived; neither fornicators, nor idolaters, nor adulterers, nor effeminate, nor homosexuals, 10 nor thieves, nor the covetous, nor drunkards, nor revilers, nor swindlers, will inherit the kingdom of God.
Galatians 5:16-23 (NASB)
16 But I say, walk by the Spirit, and you will not carry out the desire of the flesh. 17 For the flesh sets its desire against the Spirit, and the Spirit against the flesh; for these are in opposition to one another, so that you may not do the things that you please. 18 But if you are led by the Spirit, you are not under the Law. 19 Now the deeds of the flesh are evident, which are: immorality, impurity, sensuality, 20 idolatry, sorcery, enmities, strife, jealousy, outbursts of anger, disputes, dissensions, factions, 21 envying, drunkenness, carousing, and things like these, of which I forewarn you, just as I have forewarned you, that those who practice such things will not inherit the kingdom of God. 22 But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness, 23 gentleness, self-control; against such things there is no law.
Revelation 21:7-8 (NASB)
7 He who overcomes will inherit these things, and I will be his God and he will be My son. 8 But for the cowardly and unbelieving and abominable and murderers and immoral persons and sorcerers and idolaters and all liars, their part will be in the lake that burns with fire and brimstone, which is the second death.
Some would say “Repentance is between the sinner and God (or possibly a person the sinner has offended). It isn’t up to US to determine who gets to be forgiven, or under which set of visible conditions. I think a lot of people on this board miss that. WE (Christians) don’t have the right to decide the repentance level of someone’s heart before deigning to socialize with them. Or show them a basic level of respect.”
But CHRIST said otherwise.
15 “If your brother sins, go and show him his fault in private; if he listens to you, you have won your brother. 16 But if he does not listen to you, take one or two more with you, so that by the mouth of two or three witnesses every fact may be confirmed. 17 If he refuses to listen to them, tell it to the church; and if he refuses to listen even to the church, let him be to you as a Gentile and a tax collector.
3 Be on your guard! If your brother sins, rebuke him; and if he repents, forgive him. 4 And if he sins against you seven times a day, and returns to you seven times, saying, ‘I repent,’ forgive him.”
PAUL taught otherwise.
1 Corinthians 5:1-2
1It is actually reported that there is immorality among you, and immorality of such a kind as does not exist even among the Gentiles, that someone has his father’s wife. 2 You have become arrogant and have not mourned instead, so that the one who had done this deed would be removed from your midst.
1 Corinthians 5:9-13
9 I wrote you in my letter not to associate with immoral people; 10 I did not at all mean with the immoral people of this world, or with the covetous and swindlers, or with idolaters, for then you would have to go out of the world. 11 But actually, I wrote to you not to associate with any so-called brother if he is an immoral person, or covetous, or an idolater, or a reviler, or a drunkard, or a swindler—not even to eat with such a one. 12 For what have I to do with judging outsiders? Do you not judge those who are within the church? 13 But those who are outside, God judges. Remove the wicked man from among yourselves.
We must let people know they need Christ. If someone claims to be a Christian, they must know they need to stop sinning.