Mike Ratliff writes:
The Reformed doctrine of The Perseverance of the Saints does not teach license to sin. It teaches that God’s grace works in the lives of believers through their sanctification to mortify their sins and keep them from falling away. In fact, it teaches that perseverance is the indicator of Christian genuineness. Those who persevere to the end are the ones who are truly saved. Those who do not were never saved to begin with. There is no being saved, then unsaved, then saved, then unsaved… No, the Word of God teaches us that our sins are forgiven and those sins are cast as far as the East is from the West.
You can read the rest of the article here.