"Dad, how do we know we have 'the truth' when other people claim to have 'the truth'?"
My twelve-year-old son is starting to ask the big questions...
Why do we want to know that we believe "the" truth? Does God give rewards for good catechisms? Are we better than other people when our profession of faith is more accurate than theirs? What motivates our desire to possess the truth? Are we seeking value? Acceptance? Superiority?
The only reward we can get for the truth is itself.
Jesus said, "You will know the truth, and the truth will make you free." John 8:32
The value of truth is in the fruit it bears. Truth is confident and secure in its existence even if all the world calls it a liar. People who possess the truth walk in the peace truth possesses. When the criticisms of others do not threaten us, we know that we are walking in the truth.
Heavily criticized by His opponents, Jesus waved their criticisms away with a shrug of the shoulders, freely allowing his opponents to choose their positions. Jesus realized that His critics would not be satisfied with any answer He could give:
"Children sing this song:
'You didn't dance when we played the flute,
You didn't cry when we sang the dirge!'
"What am I saying?" Jesus said, "When John the Baptist appeared, he didn't eat the normal food and drink others enjoyed—and people said, 'What's wrong with him? Does he have some demon?' But then I come along, eating and drinking normally, and people say, 'Ooh, look at him—a drunkard and a party guy, hanging around with all the riff-raff!' But you know, the truth does not need outside validation. The proof is in the pudding."
(Matthew 11:17-19, my paraphrase).
We know we have the truth when we can stand confidently and even suffer for what we confess. We don't suffer for the truth because we are scared of arbitrary punishment or wish to obtain a reward for martyrdom, but because we know that confessing anything else will mean slavery for our soul.
If any insecurity manifests on our part when we come to the defense of the truth, that insecurity reveals a misguided reason for possessing truth, which means we believe something untrue about truth! The truth does not reward us with peace as a "thank you" for believing it. The truth is peace and cannot produce anything less.
The person who lives in righteousness, peace, and joy in the Holy Spirit, is a person who is walking in the one and only truth. You cannot argue with results. To quote Jesus without paraphrasing:
"Wisdom is vindicated by her deeds." Matthew 11:19