Foolishness is common.  The word for 'fool' in English is derived from the Latin for 'windbag' (contemporary English might use 'airhead'!), and the Greek word used here simply means 'without understanding'.  Although many people like to invent and share their own ideas, if they do not understand the truth then whatever they think and say is empty, useless and confusing to others.  Whatever religion is followed, unless it is focussed on Jesus Christ as the sin-bearing Saviour and King to be obeyed – it will be powerless to change lives and offensive to God (2 Timothy 3:1-5).    
 
Two people were walking the seven miles back from Jerusalem to their home in Emmaus.  Then Jesus appeared alongside them but they did not know who He was (Luke 24:13-16).  Having told Him what they thought about Jesus (Luke 24:19-24), Jesus then said what He thought about their ideas, “How foolish you are …”  They did not understand what had happened: here are four reasons.  Firstly, it was outside their experience; they could not understand it by reference to anything they had already seen.  Secondly, they did not fully know who Jesus was, assuming that He had no more power over the grave than any other person (even though they knew He had brought dead people back to life). Thirdly, they did not believe the Old Testament Scriptures which described His death and resurrection.  Fourthly, they did not believe His own accurate and detailed predictions of His sufferings and rising again.
 
Their foolish ideas were simply the best solution they could invent to explain the circumstances.  Without understanding who Jesus was, why He chose the cross and how He could rise again, they had no way of making sense of it all.  Their foolish thoughts and words were inevitable and hopeless.  So, Jesus told them about Himself by using the Old Testament Scriptures.  He was not just a man, but also the Son of God.  He was not a victim of cruel people, but chose to be God's sacrifice for the sins of all people (John 10:18).  He was not a national liberator, but the Saviour of everybody in the world (John 4:42).
 
Many of our friends and colleagues are confused about Jesus.  They do not know His identity, His purpose on earth or how to relate with Him.  And there is no way to gain that understanding unless God reveals it to them.  But that revelation involves us!  We cannot make people believe but unless we provide the truth about Jesus, there is nothing for them to believe (Romans 10:13-14).  In the same way that Jesus used the Bible to help the two walkers understand, we have the same resource for helping people understand Jesus.  The Bible continues to be the only and indispensable source of knowledge about God (2 Timothy 3:15-16).  Read it, memorise it, meditate on it, pray about what it says, accept it's truth, obey what it says, trust it's promises, rejoice in the security it reveals ... and share it with others because God has put His truth there.  Don't just pray for your friends or show them the best bits of your life - open up the Scriptures to them, and let God speak into their confusion straight from His Word!