When we read about the two sons in Luke chapter 15, we can see that both brothers, missed the point.
One of them thought, that because he was doing everything his father required of him to do, deserves to be given good gifts from his father, for his own obedience and performance. So he thought, that because he was doing everything right in the eyes of his father, he deserved to be given good gifts. He thought himself of worthy of the the good gifts, because he has worked for them.
The other brother, because of his sinful life, and bad performance, thought that he could never again deserve to receive anything good from his father. He thought that in order to receive a good acceptance and good things from his father, he had to live a righteous life, and do things which his father would expect from him to do. But because he messed things up, he started to believe, that it is finished, and there would not be anymore acceptance or a gift from his father.
Both of the brothers, were looking at the wrong thing, and that wrong thing were their own actions in life. Everything depended on their own performance, on their own conduct, on their own works.
Both of them completely ignored the fact, that they both belonged to their own father, as his own children. Regardless of their way of life, they were the children of their own father, and nothing could change that ever.
But the father, was emphasizing to both of them, the fact, that because both of them were his own children, that is enough, for him to accept them, and give them good gifts, just because he was their own father, and they were his children. It had nothing to do with how they lived, or what they did.
We as Christians, have the divine nature in us, by being born again from the Holy Spirit, and being given the right, to become children of the living God, our Father in heaven.
We are God’s children, we are part of him, and his Holy Spirit lives in us. We belong to him, because we have accepted everything that Jesus did for us on the cross, and by his Resurrection from the grave.
That is the grace of God, that he gives us every good thing, nob because of how holy lives we live, but because we belong to him as his own children. That is his own grace given to us as sons and daughters.
We have to live a holy life, but that is never why God gives us good gifts. It is all because of him, and not because of us.