It's in Moroni, last chapter, almost last verse. Chapter 10, verse 33. I'm only going to talk about the first line.
Is perfect in Christ different from being perfect in your own right? The real interesting part is "and deny not his power". Not only is grace necessary but also not denying Gods power. Why on earth would anyone deny the power of Christ? Mornoi here tells us a pre req of being sanctified is to not deny Gods power. Wonder why he said that unless he knew the audience would be guilty of it?
So what does it mean to deny Gods power? And why would anyone ever do such a thing?
I think to deny something means to reject or refuse it. To not accept. To replace it with something else. In our pride to think we don't need it. Confining it to a warm fuzzy. Foolishly thinking it doesn't apply to your case. Believing you are too lost, or already plenty righteous or "self" righteous as the case may be. Stubbornly thinking it's obtainable only via striving, or being good enough for long enough. That denies Gods power. Why does this happen? Often it's our pride. Perhaps we are so caught up in worldly power that Gods power isn't even on the radar screen because it's never been experienced. Ignorance I think is a form of denying Gods power. There are many others. You could ignore it, fail to recognize it. You could assume God has given his power to men and therefore that's all you need. (2 Ne. 28: 5, 31) Yeah...don't do that.
The opposite of denying Gods power would be believing in it, trusting it, exercising faith in, and receiving it fully. Takes humility but well worth any price. It will bring Gods power according to Moroni. Man is nothing next to Gods power. I think Moroni knows what he is talking about. Maybe repentance in this verse = stop denying Gods power and start believing. Why apologize to God for mistakes or wrongdoing, all the while denying his power? Hum.... thoughts like that may lead somewhere.