This particular proverb is based on the previous verse. That verse deals with those who conceal versus those who confess and forsake their sin. This verse is a reminder to us about another comparison. This one is those who fear God versus those who harden their heart. That is what happens when we become aware of sin in our lives. We have a choice at that point as to whether we are going to fear God and deal with our sin - or - whether we are going to harden our hearts and think that sin is not that big of an issue. Some even deny that sin exists and in so doing, put another crusty layer of hardness from ungodly philosophies over their heart.
When we become aware of sin we should fear God. We should fear God because He is holy and sin will break our fellowship with Him. As a holy God, we should also fear because His great love for us will respond with discipline in our lives to get us to turn from sin. Anyone who is even remotely familiar with the passages in the Old and New Testament where God responds to sin, should know that good things are NOT going to happen when we choose sin. Even worse things are in store if we not only choose sin - but them add to our sin by rejecting the conviction of the Holy Spirit when He seeks to alert us to our rebellion against God's Word. Just naming names and places should remind us of this. Sodom and Gommorah, Pharaoh, the Egyptian army at the Red Sea, Dathan and Abiram, Achan, Nadab and Abihu, David and Bathsheba, and Annanias and Saphira are names and places that should immediately make us aware that God takes sin seriously. Then there is that whole "judgement seat of Christ" thing, as well as the "lake of fire" in the book of Revelation that should remind us that God is anything but "pro-sin" in His dealings with mankind. Therefore we grasp and see that there would be a blessing on the man who "fears always," when it comes to sin. This does not mean that this man is cowering 24 hours a day thinking God will strike him dead at any moment. But it does mean that this man has a healthy fear of God that assists him in making godly choices - and steering clear of ungodly ones.
When sin comes to us, we do have a second choice. That choice is to "harden our heart" toward God. The wise man receives the conviction of the Holy Spirit. He embraces what God has to say to him, knowing that God loves him - and sin will be harmful. But the fool stiffens when God offers rebuke and correction. The fool doesn't want to listen - and he doesn't want any other authority than himself in his life. He completely rejects any warning that is given. He wonders what an ancient document has to do with him. Why should he restrict his desires and wants due to what the Bible has to say. Thus he hardens his heart against God and against God's Word (think here whatever God has to say about an issue.
The problem with a hardened heart toward God is that its rejection of God's Word puts him in the path of calamity. That is what we read here. God made this world - and it works best when we submit to Him. When we do not - problems are on our horizon. What I am about to say you can take to the bank. You cannot reject God's Word without causing yourself harm. There are going to be consequences for disobedience and rebellion. There are going to be consequences for following your own lusts. There are going to be consequences for choosing your own way or the ways of the world system rather than choosing God's ways. The best way to describe these consequences is with the word "calamity." This word is the Hebrew word "raah" and it means something evil or bad. Zhodiates says that this word has ten or more shades of meaning about evil according to the context where it is used. It describes absolute evil as well as various aspects of bad things that happen in our lives. One thing though about this word is that it never means something good. Thus we may not physically die immediately after rejecting God's Word and hardening our hearts toward Him - but - you can know that nothing good is going to come of it.
We have a choice day by day as to how we are going to live. Will we respect our own thinking and ways or the ways of God? Will be fear God and choose to honor and obey Him and His Word - or will will consider our own finite minds more than adequate to guide us through life? In the end, the choice that we make will yield very clear consequences. Thus we need to know as we make these daily choices that every one of them will come with either a reward or a recompense. May we be wise and choose the right way - the way of fearing the Lord - and the way of turning from sin rather than turning to it.