shadrach_ said:
It was explained to me last night by someone that justification naturally leads to a discussion on perserverance.
I guess; or sanctification.
Justification is an evaluation, an assessment by God. And it's a foregone assessment in the case of someone who is put in union with Christ by faith: that person is considered righteous by God.
With that the question naturally arises, "Well can I sin all I want then?" And Paul's reaction is horror, "No way! How can someone who died to sin [through union with Christ's death] live in sin anymore?" (cf Rom 6). His point is very interesting, because Paul then agrees, sin permeates our lives and doesn't simply disappear (Rom 7). But as the Spirit works in our lives, we come more and more to rely on the Spirit of God, to submit to His way, and thus to infuse this grace into our mortal lives and bodies (Rom 8).
This is a very terse statement from Westminster's Larger Catechism showing the distinctions between justification and sanctification in Reformed terms:
"Although sanctification be inseparably joined with justification, yet they differ, in that God in justification imputeth the righteousness of Christ; in sanctification of his Spirit infuseth grace, and enableth to the exercise thereof; in the former, sin is pardoned; in the other, it is subdued: the one doth equally free all believers from the revenging wrath of God, and that perfectly in this life, that they never fall into condemnation the other is neither equal in all, nor in this life perfect in any, but growing up to perfection."
WCF LC 77