Eternal sin
In Christian hamartiology, eternal sins, unforgivable sins, or unpardonable sins are sins which will not be forgiven by God. One eternal or unforgivable sin (blasphemy against the Holy Spirit) is specified in several passages of the Synoptic Gospels, including , , and .
Christianity and Judaism
In Christianity, forgiveness by God is promised to the repentant even though the wronged party has not forgiven the offender: "If we confess our sins, he is faithful and just and will forgive us our sins and purify us from all unrighteousness." (1 John 1:9 ) Jesus, however, requires his disciples to forgive others if they want to be forgiven themselves. Matthew 6:14,15, which follows the Lord's Prayer, says "For if you forgive men when they sin against you, your heavenly Father will also forgive you. But if you do not forgive men their sins, your Father will not forgive your sins." Forgiveness is not an option to a Christian, rather one must forgive to be a Christian.