Did Jesus’ sacrifice atone for unrepented sins?
Scenario:
You tell a little lie at the office. Later that day you die of a massive heart attack without benefit of visiting the priest to seek his forgiveness of your sins.
You die with an unconfessed sin.....do you go to Heaven or Hell?
When one becomes a Christian, all sins are forgiven...past, present and future.
Do we confess our sins to Christ on a regular basis? Yes we do. But it's not to maintain salvation. That was taken care of on the cross and when the Christian believed in Christ. It is to maintain fellowship with Him.
Colossians 2:9-14 NASB
For in Christ all the fullness of the Deity lives in bodily form,
10and in Christ you have been brought to fullness. He is the head over every power and authority.
11In him you were also circumcised with a circumcision not performed by human hands. Your whole self ruled by the flesh was put off when you were circumcised by Christ,
12having been buried with him in baptism, in which you were also raised with him through your faith in the working of God, who raised him from the dead.
13When you were dead in your sins and in the uncircumcision of your flesh, God made you alive with Christ. He forgave us all our sins,
14having canceled the charge of our legal indebtedness, which stood against us and condemned us; he has taken it away, nailing it to the cross.
This is the security of the believer.
If not, the Believer would live in a state of fear of dying without benefit of confession. If one is catholic, you'd have to be living with the priest to constantly be asking for forgiveness. That's not what Christ intended for us with His sacrifice on the Cross.
Unconfessed mortal sin - Hell. Unconfessed venial sin - Purgatory, then Heaven.