As hard as it is sometimes to just not respond to the fool with a glib, "What were you thinking?", it is necessary sometimes to set their understanding straight simply if we fail to, we allow for the fool to go on thinking their thinking was "spot on". What happens when we don't respond to the foolishness of the fool is something akin to opening the floodgates. We allow for a plethora of other stuff to continue on as though it did not matter. The fool looks for validation - when he doesn't find resistance to his actions - he takes this as validation. It is difficult to stop, take the effort and extreme amount of patience to speak with the fool, but sometimes it is the very best course of action to prevent a flood of ill-effects from his/her folly.
Answer a fool in simple terms so he doesn’t get a swelled head. (Proverbs 26:5 MSG)
Scripture is quite clear - we use simple terms to speak to the simpleton. No fool is responsive to some lengthy theological argument - but the simplicity of scripture given and explained with brevity is all he may need to understand his choice as not being the wisest. Ours is not the role of correcting the fool, but we can bring truth were it doesn't exist naturally. When we do bring truth, we do it with simplicity and accuracy. Don't beat around the bush with the fool - he cannot figure out subtlety. The fool needs direct, head-on instruction to know where he got off course and how to turn things around. He may not always hear you, but once you have put the truth out there, it is up to him to embrace it and walk in it, or to reject it and continue to stray off course.
Too many of us fail when we are faced with the folly of the fool because we want to "own" their road out of their mess. The truth is, the fool cannot learn that way. We need to allow the fool to experience the muddle of their mess and then figure the steps they need to take to get out of it. We give them the road map with the truth we share, but we don't hold their hand ensuring they read the map! The road map is in their possession once we share the truth - the responsibility to consult it with each step is theirs.
We may want to avoid the confrontation with the fool, but we sometimes cannot because their actions are impacting our lives. When this occurs, we have to know how to approach them (in simplicity), with what it is we approach (the truth), and then how to let go of them so they can embrace their actions (leaving them in the capable hands of the Holy Spirit to convict them of their missteps). Just sayin!