Because

(Proverbs 1:11 KJV)  If they say, Come with us, let us lay wait for blood, let us lurk privily for the innocent without cause:

This compound word “without cause” (2600) is fairly common in the OT.  It should be telling us something about how we respond to people.  We have often been taught that certain things, such as killing, are always forbidden.  We get the idea that we should never get angry.  Maybe that is not true based on this term.

Obviously some things are always wrong.  There is never a legitimate reason to jump someone in the dark and rob them.  But there are many things in life which are acceptable, or even necessary, if the situation is right.  You would not normally go and pound on your neighbors door at 2:00 A.M. but if his house is on fire he would understand.  You don’t normally get up and walk out of church but you might if the pastor has just denied the divinity of Christ.

At the core is our motivation and the path of reasoning we have followed. 

So?  Make sure you don’t rationalize what God will punish.  Keep seeking the guidance of the Holy Spirit and enrich your mind with the words God has given to us for that help.