In The Lion, the Witch, and the Wardrobe, it is prophesied that 4 children will come to Narnia from another world and become kings and queens, thereby saving the land from an endless winter and the reign (and life) of the White Witch. Edmund is one of those children, but early in their journey he sneaks away to tell the Witch where his siblings are:
"The reason there's no use looking," said Mr. Beaver, "is that we know already where he's gone!" Everyone stared in amazement. "Don't you understand?" said Mr. Beaver. "He's gone to her, to the White Witch. He has betrayed us all."
After Aslan's sacrifice and a long battle (where Aslan does much of the work), the 4 children are crowned kings and queens, including Edmund.
In the same way that Aslan's sacrifice covers Edmund's betrayal, so Christ's sacrifice covers all of our sins, all of our mistakes.
"If you confess with your lips that Jesus is Lord and believe in your heart that God raised him from the dead, you will be saved. For man believes with his heart and so is justified, and he confesses with his lips and so is saved." Romans 10:9-10
It's easy to believe that I can become unworthy of God's gifts by messing up. But God forgives everything and doesn't hold our sins against us, as Christ's redemption covers all of my sins - past, present, and future.
"For I am convinced that neither death nor life, neither angels nor demons, neither the present nor the future, nor any powers, neither height nor depth, nor anything else in all creation, will be able to separate us from the love of God that is in Christ Jesus our Lord." Romans 8:38-39
Failures in work cannot separate us. Not being fired, not losing an opportunity. There are no big or small mistakes that Christ's sacrifice hasn't ALREADY redeemed. God is bigger than we think, and he has already redeemed us.
But God, being rich in mercy, because of the great love with which he loved us, even when we were dead in our trespasses, made us alive together with Christ—by grace you have been saved— and raised us up with him and seated us with him in the heavenly places in Christ Jesus, so that in the coming ages he might show the immeasurable riches of his grace in kindness toward us in Christ Jesus. For by grace you have been saved through faith. And this is not your own doing; it is the gift of God, not a result of works, so that no one may boast. Ephesians 2:4-9
What mistakes are you not accepting God's forgiveness for?