وَلَا نَقُولُ لَا يَضُرُّ مَعَ الْإِيمَانِ ذَنْبٌ لِمَنْ عَمِلَهُ
We do not say that a sin cannot harm someone merely because that person has faith.
Faith is a great blessing, but it does not render wrongdoing harmless. Sin can weaken the heart, damage a person's conduct and expose the sinner to accountability.
Avoiding sin, regretting wrongdoing and returning to Allah remain necessary duties of a believer.