No Christian is trying to justify continuing in sin. Christians don't want to sin. As I've heard other preachers say, "If there was a light switch and if you turned it on it would make it so that you wouldn't sin ever again, would you click it?" A majority, if not all, Christians would turn it on. To sin is to go against the reborn nature of children of God. We are born-again. Once dead, but now made spiritually alive. We are the righteousness of God, in Jesus Christ. If you commit a sin, it doesn't take away that righteousness. It is imputed to you, as your sins were imputed to Christ.
Someone who continues in sin is not without consequence. No, it is not loss of salvation. Yes, there are people who take life times to get over a sin, but the getting over of sin is not what saves them. It is Christ and Christ alone, his finished work on the cross. It is without any added works. He is the Author and Finisher of our faith. The consequence of continuing is sin, is that sin has natural consequences. If you steal, and you're caught, there is a penalty to be paid. Yes, Jesus' blood cleanses(forgivness), but that doesn't mean that there isn't a penalty for your sin in the here and now. Look to the thief on the cross next to Jesus. He went to Paradise with Jesus, and the thief believed on Jesus. Yet, what? He still died on that cross! Why? There was a penalty for his thievery, a natural consequence. God doesn't need to punish your sins, they do well enough on their own.
A bonus: Why do you think the Holy Spirit is grieved, when you sin? It is not because you've made an offense against Him. It is because He cares for your well-being and He knows that sin has its consequences, on an individual basis and a relational basis towards others (Not towards God. Sin doesn't separate us from God, because our sins are washed by the blood of Christ and He remembers our sins no more).