Does Christ’s death mean all our sins can be forgiven?
Yes, because Christ’s death on the cross fully paid the penalty for our sin, God graciously imputes Christ’s righteousness to us as if it were our own and will remember our sins no more.
New City Catechism Q24
Why was it necessary for Christ, the Redeemer, to die?
Since death is the punishment for sin, Christ died willingly in our place to deliver us from the power and penalty of sin and bring us back to God. By his substitutionary atoning death, he alone redeems us from hell and gains for us forgiveness of sin, righteousness, and everlasting life.