But surely, there must be a limit as to how much God is willing, and prepared to forgive people of their sin.
Absolutely not. God is infinite, as is His love and mercy. If there was a limit on how much God could forgive, then this would mean that sin, a glitch and an accident in creation, would be more powerful than God.
You said whatever sin will be forgiven, as long as they repent; but I am in serious doubt as to whether this is true.
Oh, but it is. There is absolutely nothing that can separate us from the love of God.
Romans 8:38-39:
38 For I am sure that neither death nor life, nor angels nor rulers, nor things present nor things to come, nor powers, 39 nor height nor depth, nor anything else in all creation, will be able to separate us from the love of God in Christ Jesus our Lord.
Take for instance, such an example as the Nazi holocaust. Are you suggesting that Hitler will not be punished as long as he repented of his sin?
Yes, this is exactly what I am saying. If Hitler had truly repented of his sins and spent the rest of his life bitterly bewailing his sins and the consequences they had, if he had given himself over to be punished for his crimes, if he had truly undergone sackcloth-and-ashes repentance
, and done what little he could to even try to start righting the wrongs he had done, then God would have forgiven him. Not just forgiven him, but hugged him, kissed him, put a ring on his finger, slaughtered the fatted calf and made a feast to celebrate his return from death and sin. And God does the exact same thing with every one of us whenever we come to Him in repentance, no matte how many times we leave Him and come back to Him. He never tires of forgiving us and welcoming us back as His beloved children. No exceptions.
The saddest story in the Gospels is when Judas despaired of his sins and hanged himself, rather than seeking forgiveness and reconciliation from His Lord. It is sadder than the Cross, because the Cross was the victory that freed us from sin and death and opened for us the way to God. It is sadder than the story of Peter denying Jesus three times, because he immediately repented and was reconciled to Jesus after His Resurrection.
But try saying that to an Orthodox Jew, and see what happens!
God is not so hard-hearted as men. Even if the entire world didn't forgive Hitler, God would welcome him as a prodigal son if he repented, and the angels would have rejoiced that so great a sinner was not lost, but realized the error of his ways and came home. It is not the will of the Father that even the least of us should perish. Not Hitler, not Judas, not Stalin. There is nobody that God wants to perish, and therefore, there is nobody and nothing that God isn't willing to forgive.
As I am sure, there are many who would be offended by the inference you can make, according to what you have said.
So I would be grateful if you could clarify this point, please.
If there are any who are offended that every single one of us has the chance to be forgiven for the absolute worst sins we can even think of, then
let them be offended. The way of bitterness and hatred is not a fun road to walk on. It destroys us.