Dear Questioner,

My take on this is that the sin that is called deadly is mortal sin.

More than simple prayer is needed to cleanse the soul from the guilt due to mortal sin — the Sacrament of Confession is necessary to reconcile one to God and His Church.

Paul

Questioner-of-all-things,

It is referring to mortal and venial sins.

After one dies, they can't sin so there is no such thing as eternal sin.

There is the penance or satisfaction that has to be made for sins that have been forgiven before we pass from this earthly life to our particular judgment, but there's no such thing as eternal sin.

Hope this helps,

Mike