What is the appropriate response and advice for someone who commits sins and justifies them by saying, "Indeed, Allah is All-Forgiving, All-Merciful"?

Committing sins while relying on God's mercy and forgiveness is ignorance and a sense of security from God's plan. As God Almighty said: "None feel secure from the plan of Allah except the people who are losers." The Prophet (peace and blessings be upon him) narrated from his Lord: "By My Glory, I will not combine two fears and two securities for My servant. If he fears Me in this world, I will grant him security on the Day of Resurrection. And if he feels secure from Me in this world, I will make him fear in the Hereafter." And "All of my Ummah will enter Paradise except for those who refuse." It was asked: "Who are those who refuse, O Messenger of Allah?" He said: "Whoever obeys me will enter Paradise, and whoever disobeys me has refused."