The only unpardonable sin is the rejection of Christ’s work on the cross (John 1:29; 3:18,36). This sin is related to the convicting ministry of the Holy Spirit, and if this truth is rejected, it is blasphemy of the Holy Spirit (Genesis 6:3; John 16:7-11; Hebrews 10:29).
This is the only unpardonable sin in existence today.