Eternal sin
In Catholic teaching there are six sins that blaspheme against the Holy Spirit. They are: Several passages in the Bible are frequently interpreted as referring to the unforgivable sin:
Seven deadly sins
With Christianity, historic Christian denominations such as the Catholic Church and Protestant Churches, including the Lutheran Church, recognize seven virtues, which correspond inversely to each of the seven deadly sins. 
Confession is the act of admitting the commission of a sin to a priest, who in turn will forgive the person in the name (in the person) of Christ, give a penance to (partially) make up for the offense, and advise the person on what he or she should do afterwards.