Purposes of Christ's Death: 1 Peter 3:18
Because Christ also suffered once for sins, the just for the unjust, to bring you to God, by being put to death in the flesh. (NET)There are lots of not-so-clear things in the verses after this one, but this particular verse is pretty straight forward. The purpose statement given here for Christ's being put to death—or Christ's suffering for sins—is "to bring you to God." This, of course, is pointing to the reconciliation that Christ's death brings.
Reconciliation goes two ways: God is reconciled to human beings, and human beings are reconciled to God. Christ, the just one, suffers in place of the unjust ones (that would be sinners like you and me), and on the basis of what is accomplished by his vicarious suffering, the sin that stands between God and sinners is taken out of the way. Because of Christ death, God can reach out to cause sinners to be reconciled to himself. Sinners can be brought to God because Christ died.
Another purpose for Christ's death is to bring people to God.