Are there sins for which there is no repentance?

Greetings and blessings. 

1. There is nothing that stands before repentance!! King Manasseh of Israel sinned grievously for 22 years, yet in a time of distress, after realizing that no idol could save him, he turned to the Creator of the world and asked Him to save him, and he returned in full repentance. Hashem made a special effort beneath the Throne of Glory to accept him in repentance. Likewise, any Jew whatsoever can return in complete repentance, and he is accepted. 

2. Here are the words of the Rambam (Laws of Repentance, Chapter 4): (a) One who causes many to sin and generally prevents many from doing mitzvot. (b) One who leads his friend from a good path to an evil one, such as one who seduces and misleads. (c) One who sees his son engaging in evil and does not rebuke him, thereby sharing responsibility, and generally anyone who could stop others from sinning but does not. (d) One who says, "I will sin and repent," implying he relies on the Day of Atonement to absolve him. Five things close the gates of repentance for their doers: (a) One who separates himself from the community, so that when the community repents, he is not among them and does not share in their merit. (b) One who disputes the words of the sages, causing himself to separate from them and not knowing the paths of repentance. (c) One who mocks the mitzvot, neglecting to pursue them since he despises them. (d) One who disgraces his teachers, causing himself to be pushed and distracted, so that when he is confused, he finds no teacher to teach him the true way. (e) One who hates rebuke, thus refusing the path of repentance provided through rebuke, as the Torah commands to remember, not forget, and the prophets admonished Israel until they repented. Therefore, a wise, elderly, God-fearing man beloved by the community must chastise the many and return them to repentance; one who hates rebuke does not listen and thus remains in sin, seeing his sins as good. Five things that make it impossible to fully return in repentance because they are sins between a person and his fellow for which he does not know to bring his friend back or ask forgiveness: (a) One who curses the rabbis but has not cursed a known individual to obtain atonement. (b) One who shares with a thief, not knowing whose theft it is, benefiting from and aiding the thief. (c) One who finds lost property and does not announce it to return it, thus when he repents he does not know to whom to return it. (d) One who consumes oxen of the poor, orphans, and widows—people who are unknown, unfortunate, and wandering city to city, so their oxen are not identified and thus not returned. (e) One who accepts a bribe to pervert justice, not knowing how far the corruption extends and thereby sins himself. Five things that make it impossible to return from because they are light in the eyes of many, causing sinners to deceive themselves that they have not sinned: (a) One who eats from a meal not sufficient for its owners, effectively stealing, yet imagines he has not sinned because it is permitted. (b) One who uses the poor person's utensils, declaring in his heart that they are not lacking and so he has not stolen. (c) One who looks upon female nakedness thinking it is nothing, unaware that such viewing is a great sin causing the body to be analogous to nakedness. (d) One who honors his friend's disgrace, thinking it not a sin because his friend is not there and was not embarrassed personally but rather through his actions and wisdom. (e) One who suspects the righteous, thinking it not a sin, saying, "What did he do to me? There is nothing, only suspicion," unaware this is a sin likened to wrongdoing while conscious. Five things that draw one to them constantly, making it difficult to separate, all bad character traits for one striving for repentance: gossip, lashon hara (evil speech), anger, evil thoughts, and befriending the wicked to learn from their deeds. Solomon said in Proverbs 13:20, "He who walks with fools shall be harmed." As explained in the Laws of Character Traits, everyone must always avoid these, especially one aspiring to repentance. All these things and their like, even though they delay repentance, do not prevent it unless the person repents from them, in which case he is a penitent and has a share in the world to come. 3. One who goes toward an evil culture and regrets his good deeds loses the mitzvot. 4. In certain cases, due to sins such as heresy, idolatry, or other various reasons, a soul may reincarnate among the nations, and its rectification is through conversion and return to the true religion. Apart from this, there are holy souls from the root of holiness—the root of Israeli souls—who were exiled into impurity at the sin of Adam as explained extensively by the Kabbalists; they are born among the nations and upon their conversion are freed from captivity and return to their source. Success, Binyamin Shmueli