Justification Vs. Self-Justification

Self-justification is the deepest impulse in the fallen human heart. We might sincerely agree with the biblical doctrine of justification by faith alone. But deep in our hearts, it isn’t that simple, is it? Gerhard Forde helps us see ourselves:
The problem lies in the fact that the Old Being will not and cannot hear gospel no matter what one says. The Old Being will only use whatever is said as part of the protection, solidification in the causa sui project [the self-justifications we build], and translate it into or see it as a ratification of the legal system. That is, the Old Being will turn whatever one says into law.
We deeply desire to save ourselves. At the same time, our sin includes a hidden filter blocking out clarity about our sin. Martyn Lloyd-Jones describes our lack of self- awareness:
You will never make yourself feel that you are a sinner, because there is a mechanism in you as a result of sin that will always be defending you against every accusation. We are all on very good terms with ourselves, and we can always put up a good case for ourselves. Even if we try to make ourselves feel that we are sinners, we will never do it. There is only one way to know that we are sinners, and that is to have some dim, glimmering conception of God.
Our mentality of blind self-justification makes Paul’s letter to the Galatians endlessly relevant to us believers. We don’t get rid of Galatianism by embracing grace-justification. But, by embracing grace-justification, we do gain a remedy for our compulsive self-justifications. The Puritan William Fenner taught us to see justification by faith alone as a constant resource:
As we sin daily, so he justifies daily, and we must daily go to him for it. Justification is an ever-running fountain, and therefore we cannot look to have all the water at once.

A Beautiful Gospel