Bismillahir Rehmanir Raheem
The Mercy and Forgiveness of Allah Almighty on Mankind:
I first of all would like to start this beautiful topic about Allah Almighty's Mercy by showing this Saying from our beloved Prophet Muhammad sallallahu alaih wasallam:
Narrated Hazrat Abu Huraira radi Allahu anhu: "Allah's Apostle sallallahu alaih wasallam said, 'When Allah completed the creation, He wrote in His Book which is with Him on His Throne, 'My Mercy overpowers My Anger.' ' (Translation of Sahih Bukhari, Beginning of Creation, Volume 4, Book 54, Number 416)"
There are ample Noble Verses from the Noble Quran that talk about Allah Almighty's Mercy and Forgiveness. In fact, when I check the index in the back of the Noble Quran that I have, I find that there are tons of references of Noble Verses that talk about Allah Almighty's Mercy and Forgiveness. Without exaggeration, just by looking at the references, I would say there are at least 100 Noble Verses.
Let us look at few of them that I selected:
"Say: "To whom belongeth all that is in the heavens and on earth?" Say: "To God. He hath inscribed for Himself (the rule of) Mercy. That He will gather you together for the Day of Judgment, there is no doubt whatever. It is they who have lost their own souls, that will not believe. (The Noble Quran, 6:12)"
Disbelievers' sins will be all forgiven for them when they embrace Islam: "Say to the Unbelievers, if (now) they desist (from unbelief), their past would be forgiven for them; but if they persist, the punishment of those before them is already (a matter of warning for them). (The Noble Quran, 8:38)"
"The Lord of the heavens and the earth, and all between,- Exalted in Might, able to enforce His Will, forgiving again and again. (The Noble Quran, 38:66)"
If we are sincere, our daily sins are almost always forgiven: "Those who avoid great sins and shameful deeds, only (falling into) small faults,- verily thy Lord is ample 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: He knows best who it is that guards against evil. (The Noble Quran, 53:32)"
If you ask Allah Almighty for forgiveness, then He'll forgive you: "If any one does evil or wrongs his own soul but afterwards seeks God's forgiveness, he will find God Oft-forgiving, Most Merciful. (The Noble Quran, 4:110)"
If you are grateful to Allah Almighty, then He'll give you more: "And remember! your Lord caused to be declared (publicly): 'If ye are grateful, I will add more (favours) unto you; But if ye show ingratitude, truly My punishment is terrible indeed.' (The Noble Quran, 14:7)"
Be sure that Allah Almighty is always Willing to forgive all of your sins: "Say: 'O my Servants who Have transgressed against their souls! Despair not of the Mercy of Allah: for Allah forgives all sins for He is Oft-Forgiving, Most Merciful. (The Noble Quran, 39:53)"
The use of the word "Say" in this Noble Verse means that Allah Almighty wants us to always remind each others by reciting this Noble Verse to those who need it.
Allah Almighty accepts our many sins: "If God were to punish men according to what they deserve, He would not leave on the back of the (earth) a single living creature: but He gives them respite for a stated Term: when their Term expires, verily God has in His sight all His Servants. (The Noble Quran, 35:45)"