My Proof that God Forgives

I was wondering if there was a way to know that God will forgive no matter what someone has done. The following came together in my mind.

What would define "the most difficult to forgive"? For me, it would be the most personal offense. Something in regards to my family, perhaps? But I can imagine myself not forgiving my family (I've done this once or twice, although God has adjusted me) which kind of nullifies that offense as being "the worst."

For me, it would have to be something offensive as it pertains to my ideals, values, etc. - things in my brain. [While I am going to see God through this lens of myself, I am not claiming this is God's only perspective. I am elaborating on this aspect of God only] The following scenario came to mind.

When Jesus is towards the end of 3+ years of Gospel-recorded activities, He has been emphasizing the servant role for Himself and His disciples. In this context, James and John and their Mommy come to Jesus and ask to be First.

If I were Jesus, I would kick them out of my discipleship group (sic). How could they ask, nay, manipulate unto the goal of me-first, anti-servant?!?! Hadn't this been the POINT of all human-to-human interactions? And to have 2 of the 3 closest disciples pull this stunt! If I were Jesus I would have toasted them right there. Or I would have deliberately and recordably gone back in time, with Mark or Q or someone, and changed my calling of the Boys Of Dumber.

Yet when it's all over, one is His best friend and one is the pillar of the Church.

For me, that would have been an unforgivable offense - in my very face, ASK for me to go 100% contrary to that which is most important to me, for the sake of destroying one of the top 3 purposes for my existence. And they SO should have known this!

From a mental/rational point-of-view, I cannot see God as being unable to forgive.