Someone, let's call him "person A"-- says to the class in general
"Ah, it's ok to get C's as grades as long as you pass the class. Don't work hard."
It's bad advice. I know that. Working hard, knowing things well, and doing the best you can-- will result in good grades. If I were to tell him that, he would say to me "You don't understand what I'm saying." But the truth is, he is the one who doesn't understand:
Prov 10:4 (ESV):
A slack hand causes poverty, but the hand of the diligent makes rich.
Romans 12:1-2 (King James Version):
I beseech you therefore, brethren, by the mercies of God, that ye present your bodies a living
sacrifice, holy, acceptable unto God, which is your reasonable service.
And be not conformed to this world: but be ye transformed by the renewing of your mind, that ye
may prove what is that good, and acceptable, and perfect, will of God.
Proverbs 29:9 (ESV):
If a wise man has an argument with a fool, the fool only rages and laughs, and there is no quiet.
The implication is that it is better for the wise man not to say anything at all.
Proverbs 23:9 (ESV):
Do not speak in the hearing of a fool, for he will despise the good sense of your words.
Also note Prov 25:26 (ESV):
Like a muddied spring or a polluted fountain
is a righteous man who gives way before the wicked.
Take care who influences you.
1 cor 15:33 ESV:
Do not be deceived: "Bad company ruins good morals."
The principle of not speaking wisdom to fools who will disregard your good advice is reflected in the NT, in what Jesus Christ said:
Mat 7:6 ESV:
Do not give dogs what is holy, and do not throw your pearls before pigs, lest they trample them underfoot and turn to attack you.
The best option, then, is not to say something to the fool which you know he's going to disregard and call you a fool. Why? Because if you know he won't understand simply by telling
him-- but he might understand if he sees the result of your belief in God, coming from your knowledge and obedience of the Scriptures, and your works of faith in Christ Jesus. Works are evident in each person's life to see what kind of functional lifestyle they have; works in many ways are greater than solely words (when talking per se about man, besides Jesus, who was man and God, and is God and is the Son of God).
What I mean is: If what person A says is true, then it should be reflected in his lifestyle if he's successful, functional and well, or not.
We see that in the book of Luke, in verses 8:16-18 (ESV), Jesus Christ said:
No one after lighting a lamp covers it with a jar or puts it under a bed, but puts it on a stand, so that those who enter may see the light. For nothing is hidden that will not be made manifest, nor is anything secret that will not be known and come to light. Take care then how you hear, for to the one who has, more will be given, and from the one who has not, even what he thinks that he has will be taken away."
Jesus wants us to think and reason correctly.
Matthew 21:28-32 (ESV):
"What do you think? A man had two sons.
And he went to the first and said, "Son, go and work in the vineyard today."
And he answered, 'I will not,' but afterward he changed his mind and went.
And he went to the other son and said the same. And he answered, 'I go, sir,' but did not go.
Which of the two did the will of his father?"
They said, "The first."
Jesus said to them, "Truly, I say to you, the tax collectors and the prostitutes go into the kingdom of God before you.
For John came to you in the way of righteousness, and you did not believe him, but the tax collectors
and the prostitutes believed him.
And even when you saw it, you did not afterward change your minds and believe him.
The words of Jesus are authoritative.
When you read this it might feel like the correct answer to Jesus's question "Which of the two did the will of his father?"
was the guy who said "I go, sir," but did not go, but ACTUALLY, Jesus helps the chief priests and elders see that the one who did
his father's will was actually the one who WENT and DID what his father told him to do, even though initially he said he would not.
He repented. We can use our minds to reason things through, knowing what God tells us from Scripture.