The Quran

Preface

الَّذينَ يَجتَنِبونَ كَبائِرَ الإِثمِ وَالفَواحِشَ إِلَّا اللَّمَمَ ۚ إِنَّ رَبَّكَ واسِعُ المَغفِرَةِ ۚ هُوَ أَعلَمُ بِكُم إِذ أَنشَأَكُم مِنَ الأَرضِ وَإِذ أَنتُم أَجِنَّةٌ في بُطونِ أُمَّهاتِكُم ۖ فَلا تُزَكّوا أَنفُسَكُم ۖ هُوَ أَعلَمُ بِمَنِ اتَّقىٰ

Yusuf Ali

Those who avoid great sins and shameful deeds, only (falling into) small faults,- verily thy Lord is ample¹ in forgiveness. He knows you well when He brings you out of the earth, And when ye are hidden in your mothers? wombs. Therefore justify not yourselves:² He knows best who it is that guards against evil.

God’s attributes of Mercy and Forgiveness are unlimited. They come into action without our asking, but on our bringing our will as offerings to Him. Our asking or prayer helps us to bring our minds and wills as offering to Him. That is necessary to frame our own psychological preparedness. It informs God of nothing for He knows all.
As God knows our inmost being, it is absurd for us to justify ourselves either by pretending that we are better than we are or by finding excuses for our conduct. We must offer ourselves unreservedly such as we are: it is His Mercy and Grace that will cleanse us. If we try, out of love for Him, to guard against evil, our striving is all that He asks for.