I doubt anyone this side of heaven has ever had the virtue of faith down 100% perfectly. Same with hope and love. And it’s best to just be honest with ourselves about that. All truth is good even if not always comfortable and “All truth is God’s truth” as Augustine put it. And we all start out atheists for all practical purposes.
Our justice, defined primarily by faith, hope, and most importantly, love, can be and is actually intended to be subject to growth. So we can have more or less relatively speaking. And the more we “exercise” these virtues, the more they grow, and so the more we experience their reality first hand. Grace leading to more grace as we cooperate with it, as we “invest” it as per the Parable of the Talents. But meanwhile we will still also doubt t times, to one degree or another, and sometimes lose hope, and often fail to love as we should. And through this struggle we can be tested and refined. And the possibility of falling backwards is an ever-present possibility as well. In my experience the struggle is a good one, grueling at times, and not over until God says so in any case. Here’s an indirectly related, but relevant to your question, teaching from the catechism:
1732 As long as freedom has not bound itself definitively to its ultimate good which is God, there is the possibility of choosing between good and evil , and thus of growing in perfection or of failing and sinning. This freedom characterizes properly human acts. It is the basis of praise or blame, merit or reproach.