I Thess. 5:19-22 Do not stifle the Holy Spirit. Do not scoff at prophecies, but test everything that is said. Hold on to what is good. Keep away from every kind of evil.
We stifle the Holy Spirit whenever we do not hear or listen to what He is saying to us. He speaks to us mainly through the Word of God and there are so many different ways we fail to hear Him speak as we read it. We often read it with our minds already made up as to what it says, instead of just reading it for understanding of what is being said. We do not set aside quiet time when we read it so we can hear the Spirit speak. We do not read enough of it to get a sense of what is being said. We do not read it with our minds engaged. We do not read it with the idea that we can learn new things. We don't read it knowing we need to hear from God.
We stifle the Spirit when we shut out the Word being proclaimed. We sometimes hear the Word proclaimed and do not evaluate it in light of the Word. Instead of thinking over a text for ourselves, we blindly accept what others say about it. We need to put everything we hear to the test of God's Word before we accept it. In order to do that, we must engage our minds when the Word is being spoken.
We need to hold on to that which is good and discard that which is not. If we hear the Word being spoken, we take that which is good and discard that which is not good. Just because someone may say it is true, doesn't make it true.
We are to keep away from every kind of evil. In our minds there should be a warning sign in front of evil when we encounter it. WARNING: DANGER AHEAD. DO NOT GO ANY CLOSER. IT IS DEADLY TO YOUR SOUL. We dare not take evil lightly. Stay away from it for the health of your soul.