Is there any sin which cannot be forgiven?

There is a sin that Jesus called unforgivable, and it’s often called "blasphemy against the Holy Spirit." This means refusing to accept the work and truth of the Holy Spirit about Jesus, even when you clearly know the truth. The Pharisees did this when they saw Jesus do miracles but said it was from the devil, not God (Mark 3:28-29, Matthew 12:31-32). This sin is unforgivable because it shows a hard, unrepentant heart that permanently rejects Jesus. Today, this sin is understood as persistently refusing to accept Christ and His salvation.

So, the one sin that cannot be forgiven is the ongoing rejection of Jesus and the Holy Spirit’s work to bring you to Him. If you’re worried about having done this, that worry is a good sign you haven’t, because people who reject Jesus don’t usually care or seek forgiveness (Mark 3:28-29; Hebrews 6:4-6; John 16:8). God wants everyone to be saved, but forgiveness only comes through faith in Jesus.

In short, rejecting Christ forever is the only sin that cannot be forgiven. Every other sin can be forgiven when you turn to Jesus with a repentant heart.