2 Chronicles 6:30
Then hear thou from heaven thy dwelling place, and forgive, and render to each whose heart thou knowest, according to all his ways (for thou, thou only, knowest the hearts of the children of men).
One of the mysterious truths of our Faith is that we cannot know our own hearts. God only knows the hearts of the children of men, even those hearts that happen to beat in our own breasts. We need look no further than St. Peter to see this. When he said he would go with Jesus to prison and to death, he really thought he meant it. Only Jesus knew he didn’t. So it is a complete waste of time to spend a lot of time navel-gazing and asking ourselves if we really trust God, etc. All this does is turn our eyeballs inward where it’s dark. The devil loves the “Do I really trust God?” questions. They afford him endless hours of amusement. For of course, every answer in the affirmative can be immediately followed with “Did I really mean that?” etc. ad nauseam. The question the devil hates is “Is God trustworthy?” For that points us not to our own mental echo chambers and the vain attempt know our own hearts, but to an actual object: God. Point your heart and prayers there and he will render unto you what you ask of him: forgiveness and the life of the Blessed Trinity himself. For he knows what you need since he knows your heart.