Can the just avoid serious sin and thus persevere to the end? Some people consider this a false problem. They said that the just are incapable of sinning, that the sin of a man is proof that he has not yet been justified; and hence the truly just need not bother about observance of the commandments. This heresy contradicts St. Paul: “Let him who thinks he stands take heed lest he fall.” (1 Corinthians 10:12) No one, therefore is to think himself confirmed in grace unless God reveals this to him.
There is not one scripture that substantiates the idea that we no longer have to bother observing the law. I totally agree with you there. Jesus didn’t come to abolish it, He came to fulfill it for us. Just because Jesus fulfilled it so that we didn’t have to, we are still obligated to obey it. Obedience has shifted to, having to obey so that we aren’t punished to obeying because we want to out of love and gratitude.
It is then an article of faith that the just man can persevere to the end. The divine assistance ought always to be implored even by the reborn and the justified that they may come to a good end or persevere in good works. Perseverance requires a special gift of grace. Christ and St. Paul exhort the faithful to pray unceasingly for grace. The need of it arises from the weakness of the human will which, on account of the revolt of the flesh against the spirit, has not in itself the power always to stand fast in virtue/QUOTE]
It seems to me that there is a mix up of ideas here when we talk about works and perserverence. First, the bible is very clear that Jesus Christ took care of the punishment for all of our sin, once for all (1 Peter 3:18). To say otherwise contradicts scripture. So when you examine scripture, you build on that. So what is working out our salvation then? It’s just that, it’s working out the salvation that we’ve been given. It’s perservering in the truth of the gospel. It’s holding fast to the truth and not letting go of it and following some other lie.
I think the problem we run into is not understanding how deeply and fully God really loves us, even in our state of sinfulness and that He knows we can’t be righteous on our own so He made the way for us to be made righteous (Jesus:heart

. Once you get a hold of this magnificant truth in your heart, you can never be the same again. If you hold on to it, and perservere, you will be transformed from the inside out.
Thinking that you have to continually earn God’s approval and live in fear of punishment, even after He sent His one and only Son to pay the price, so gets in the way of what God wants to do with you. Here’s a picture of what it’s like:
You have been behaving badly. Your dad loves you, even if you fail him. He knows you struggle with being a good kid and he knows you just don’t have it in you to behave the way you know you should. One day, you wreck the car by hitting a tree. He knows you don’t have the money to pay for the damage but decides that he will pay for it for you. He fixes the car and tells you not to worry about paying him back but he wants you to remember that he extended that grace to you out of love. You can have the mindset of, “I have to pay dad back the money for the car so I am not obligated to him.” or “My dad really loves me no matter what. I will pay him back with my love.” Which is better?