How could God forgive me after all the sins that I have done?

God answers this question for us in Isaiah 55:7-9. God begins by calling all sinners to walk away from sin and come to him for forgiveness. It doesn’t matter what the sin or how many times it has been committed, God said that “He will abundantly pardon” (vs.7). The word “abundantly” means “exceedingly, much greater than, and plenteous.” His pardon (forgiveness) is plenty for our sins, no matter how many; His forgiveness is exceedingly greater than all the sins we could ever commit. And if we still doubted God’s ability to forgive, the text continues with this point: “For My thoughts are not your thoughts, nor are your ways My ways,” says the LORD. For as the heavens are higher than the earth, so are My ways higher than your ways, and My thoughts than your thoughts” (vs.8-9). What did God just say to us? He said that if you think you can’t be forgiven, that is NOT what He thinks. Many of us do feel that we have done some terrible things so as to never be able to obtain forgiveness, but we should not hesitate to come to God in repentance, because His ways are not our ways nor is His way of thinking our way of thinking.
Paul is a great example of the forgiveness of God. In 1 Timothy 1:13, Paul confesses that in the past he was “a blasphemer, a persecutor, and an insolent man,” and yet he received mercy from God. Why did God do that? In verse 15 Paul makes this point: “Christ Jesus came into the world to save sinners, of whom I am chief.” We may ask “how could God forgive me?” But the reality is that God has made a great plan in order to forgive us by sending His son, Christ Jesus, into the world to die on the cross for our sins. All of our sins. Notice that the verse does not say “Christ Jesus came into the world to save good, righteous people;” but rather it says that He came into the world to save “sinner.” Paul’s own testimony is added when he says “of whom I am chief.” Paul’s point is this: I am the chief of all sinners, therefore if I can be saved, then anyone can be saved. Please never allow your thoughts about your past keep you from coming to God for forgiveness. And He “will abundantly pardon.”