قُلْ يَا عِبَادِيَ الَّذِينَ أَسْرَفُوا عَلَىٰ أَنْفُسِهِمْ لَا تَقْنَطُوا مِنْ رَحْمَةِ اللَّهِ ۚ إِنَّ اللَّهَ يَغْفِرُ الذُّنُوبَ جَمِيعًا ۚ إِنَّهُ هُوَ الْغَفُورُ الرَّحِيمُ

Say: O my servants! who have acted extravagantly against their own souls, do not despair of the mercy of Allah; surely Allah forgives the faults altogether; surely He is the Forgiving the Merciful.

Therefore, no matter how sinful a servant is, he should not despair of God's vast mercy. If the sinful servant is disappointed, Satan will approach him, so God always forgives the sinful servant who repents.