"Because Jesus died on the cross,
we are all forgiven of every sin."
The forgiveness that
is in Jesus Christ is conditional upon "repentance
toward God, and faith toward our Lord Jesus Christ"
(Acts 20:21). It is a gift that God offers to everyone,
but individuals must receive it by repenting and trusting
in Christ, or they will remain dead in their sins. No
one has biblical grounds to continue in sin, assuming
that they are safe just because Jesus died on the cross.
See 1 John 3:4–6.