No. In Jainism, there is no sin that is eternally unforgivable.

But the strictest truth is this:

• Repeated pāpa creates very heavy karma.
• If a harmful act is done again and again, the bondage becomes stronger and deeper.
• It may become much harder to purify, and the soul may suffer very long परिणाम of that karma.

Still, forgiveness and purification are always possible through:

• true repentance
• pratikraman
• confession
• stopping the harmful act
• restraint and right conduct

So in Jainism, the answer is:

No sin is absolutely unforgivable, but repeated sin makes karmic bondage very severe.