Why can we not simply feel our way to assurance? Because sin blinds us to ourselves. Scripture says sin is deceitful, and it lies best to us. Every part of us has been affected, including our minds and the way we perceive our own hearts. Jesus said we are experts at spotting the speck in someone else’s eye while a log sits in our own. We are the last people qualified to grade ourselves by our feelings. So Jesus does not tell us to search our feelings; He tells us to inspect the fruit.
Think of a counterfeit bill. A good forgery can pass through hundreds of hands and fool nearly everyone. But hand it to someone at the treasury who made the original, and they know instantly that it is false, because they know exactly what the genuine article feels like. We cannot fool the One who made the real thing. One day every spiritual resume will be laid on the desk in front of the One we cannot deceive. He knows precisely what genuine faith looks like.
This is not meant to send a tender soul into despair. The apostle John, who warns us so seriously, also gives us solid ground to stand on. Again and again he writes, by this we know. We do not read our fear; we read the fruit. So do not rest your soul on your track record, your attendance, your giving, or even your answered prayers. Ask the harder and better question: am I doing all of this for Christ, or am I quietly using Christ to build something for myself?