For we labor diligently to write, to persuade our children, and also our brethren, to believe in Christ, and to be reconciled to God; for we know that it is by grace that we are saved, after all we can do. (2 Nephi 25:23)I think that many people read too much into this scripture. There is some kind of idea that we save ourselves partway and grace makes up the rest. I don't believe that's what Nephi meant. But he's right, we do have to do something. We can't be saved unless we repent. In part one, I used an analogy involving a child playing in the mud. It is clearly impossible for such a child to clean their faces using their muddy hands. The child's responsibility is to get out of the mud. The parent with the hose does the actual cleaning. Similarly, the atonement is what does the cleaning. All our efforts to save ourselves are like a child trying to clean themselves using their muddy hands. It gets nowhere. But if the child refuses to leave the mud, the hose does little good.
All we can do is repent, and remove ourselves from situations that lead to sin. The actual saving, that which cleanses us and makes us worthy, is done by the grace of Christ, through His atonement. So Nephi is exactly right. It is by grace we are saved, after all we can do.