A legalistic mindset can lead us to thinking more highly of ourselves as we ought to, as human nature disparages godly logic.
It should be concerning to us when others appear overly impressed by us (or someone else;) exalting people for what GOD is doing. We need to tell them… It’s not me you’re impressed with, it’s God working in me that impresses you; you’re impressed by HIM. They will immediately get what you are saying. We believers can learn from the errors of our forefathers, see Numbers 20:10-13.
Sometimes in the attempt to forgo legalism, we are consequently drawn to the OSAS doctrine, which is in essence, doing nothing.
It’s true we don’t do works to earn our way into Heaven, and YES, we are only saved by His Grace, not of works. See Ephesians 2:8-9. However, if we truly believe, we will truly love Him and desire to please Him, therefore, we WILL do good works. (We will use our will to choose His Will.)