The most common attitude of Muslims towards their brothers who sin in some way is that they do not consider them to be purely enough to repent.
How can that brother who commits such and such act, so shameful. Allah will never forgive
No matter how many times I advice him, that brother always return to sinning.
Subhan’Allah how great are these words for a Muslim to say about another Muslim. These who think like this should always remember, every saint has a past and every sinner had a future.
Our pious predecessor explained Allah’s forgiveness in the following way:
It is reported that a man came to ʿAlī – Allāh be pleased with him – and asked, What do you think about a man who committed a sin? He replied, He must seek Allāh’s forgiveness and repent to Him. [The man] said, He did that, but then sinned again? [ʿAlī] said, He must seek Allāh’s forgiveness and repent to Him. The man again said, He did that, but returned to sin. [ʿAlī] said, He must seek Allāh’s forgiveness and repent to Him. The man said for the fourth time, He did, but then sinned again. ʿAlī then said, Until when? Then he said, He must seek Allāh’s forgiveness and repent to Him; and not give up until it is Shaytan who is defeated [overcome].
Mentioned in Hunād b. Al-Sarī, Kitāb Al-Zuhd article 910
One must be consistent in doing what Allah had ordained, and if due to ignorance and temptations one has sinned, he should keep seeking repentance untill one has completely left it.
أَنَّهُ مَنْ عَمِلَ مِنكُمْ سُوءًا بِجَهَالَةٍ ثُمَّ تَابَ مِن بَعْدِهِ وَأَصْلَحَ فَأَنَّهُ غَفُورٌ رَّحِيمٌ
If any of you does evil in ignorance, and thereafter repents and does righteous good deeds (by obeying Allah), then surely, He is Oft-Forgiving, Most Merciful.
My Allah help us.