Yes, I was quoting you.
If God's law is written on your mind and heart, then what else could it mean besides that you never sin?
The Church teaches that even believers still sin, and are still sinners, as Robert also knows. But as you study her teachings, you find that there are two categories of sins, grave, and lighter sins. Lighter sins are forgiven or venial sins, in the sense that their commission does not affect full communion with the Body of Christ, but grave matter, grave sins, do. Committing grave sins renders a believer not in full communion, and not authorized to validly receive Holy Communion, and so in order regain full communion with her, a believer must reconcile with her, and this is administered in the sacrament of reconciliation, penance, or confession.
Before entering the kingdom, the Church teaches that we must be purified, such that we no longer sin, and are not sinners anymore, because the kingdom is holy and only holy people enter in. This purification is an ongoing process until one has been fully purged, and in most cases completes after death in purgatory.
Everybody who is in purgatory will inevitably enter the kingdom, but not before complete purification.