Sin is the disobeying of God’s commandments.
1 John 3:4 Whoever commits sin also commits lawlessness, and sin is lawlessness.
Each and every sin is punishable by eternal death.
Ezekiel 18:4 Behold, all souls are Mine; The soul of the father As well as the soul of the son is Mine; The soul who sins shall die.
Romans 6:23 For the wages of sin is death, but the gift of God is eternal life in Christ Jesus our Lord.
Jesus gave his sinless life as a sacrifice for sin, to make reconciliation for those who believe and obey the gospel. Jesus says:
Mark 3:28 Assuredly, I say to you, all sins will be forgiven the sons of men, and whatever blasphemies they may utter; 29 but he who blasphemes against the Holy Spirit never has forgiveness, but is subject to eternal condemnation
This was his answer when the Jewish leaders having seen the miracles he performed by the Holy Spirit power of God, told people that the miracles were performed by the power of a non-existent false god.
Mark 3:22 And the scribes who came down from Jerusalem said, "He has Beelzebub," and, "By the ruler of the demons He casts out demons.
Beelzebub was originally the name of an idol worshipped by Philistines at Ekron.
2 Kings 1:2 Now Ahaziah fell through the lattice of his upper room in Samaria, and was injured; so he sent messengers and said to them, Go, inquire of Baal-Zebub, the god of Ekron, whether I shall recover from this injury.
Holy Spirit powers are not available today, so it is not possible for us to commit the ‘unforgivable’ sin. In Christ, all sins can be forgiven providing we believe and obey the gospel preached by Jesus and his apostles.
After baptism we cannot live a sinless life but if we make a determined effort to obey Christ’s commandments, we are promised forgiveness of sin by confession in prayer.
1 John 1:7 But if we walk in the light (follow his commandments) as He is in the light, we have fellowship with one another, and the blood of Jesus Christ His Son cleanses us from all sin. 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.
If we ignore the gospel and continue to live a sinful life we will not be forgiven.
Hebrews 10:26 NIV If we deliberately keep on sinning after we have received the knowledge of the truth, no sacrifice for sins is left,
I hope you find this helpful.