Once upon a time Jesus told a parable of a very wealthy man and when he did he called this man a fool.
[Luke 12:20] But God said to him, 'You fool! This very night your life will be demanded back from you, but who will get what you have prepared for yourself?' NET
It's likely the world would have treated this man as more of a genius than a fool because of his enormous success in accumulating many things. Pretty much everyone could agree that there are a good number of foolish people roaming the planet and the internet. However, God and the world don't often agree on what is foolish. Definitely not everyone we think is a fool is one.
One common reason humans treat others as if they were idiots is because they don't agree on various subjects. Just because we don't agree with a person on certain issues does not make them a fool. Christians should be civil and attempt to be on “friendly” terms even with those they do not agree with.
We should be concerned about the eternal destination of even the biggest fools. God doesn't want destroyed those who are not at all Christlike and we shouldn't either.
[Ezekiel 33:11] Say to them, 'As surely as I live, declares the sovereign Lord, I take no pleasure in the death of the wicked, but prefer that the wicked change his behavior and live. Turn back, turn back from your evil deeds! Why should you die, O house of Israel?' NET
The meaning of the word fool from a biblical perspective: It is a person who refuses godly wisdom. Those who reject the God of the Bible and Jesus will not consider the teachings of the Bible to be particularly useful.
We all are sometimes foolish. To think otherwise would be believing a lie. Every single one of us has done and continues to do things that fall way short of God's ideal. It's good to be honest with ourselves because until we reach the conclusion we need to make even more progress, then we are unlikely to ask the Lord for his help in continuing the transformation.
One of the best tools to help us identify our own foolish behavior is a pretty simple one. It's coming to the realization that the easiest for us to spot foolish behaviors in others is the behavior we are most familiar with and guilty of ourselves.