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:
Christian theology
In Russian variant of Eastern Christianity, sin sometimes is regarded as any mistake made by people in their life. From this point of view every person is sinful because every person makes mistakes during his life. When person accuses others in sins he always must remember that he is also sinner and so he must have mercy for others remembering that God is also merciful to him and to all humanity.