The only unforgivable sin according to the Church is "blasphemy against the Holy Spirit"[1], which is defined as refusal of God's mercy and forgiveness [2]. [1

The only unforgivable sin according to the Church is "blasphemy against the Holy Spirit"[1], which is defined as refusal of God's mercy and forgiveness [2]. [1]: https://ucatholic.com/catechism/1864/ https://ucatholic.com/catechism/1864/ [2]: https://www.vatican.va/content/john-paul-ii/en/encyclicals/documents/hf_jp-ii_enc_18051986_dominum-et-vivificantem.html https://www.vatican.va/content/john-paul-ii/en/encyclicals/d... (see 46)