Note 18 at 1 Th. 5:19: The word "quench" as used in this instance means "to suppress, squelch" (NAHD). The Holy Spirit, as part of the Godhead (see note 4 at Acts 5:4, p. 594), is infinitely greater in power and might than any of us. Yet, amazingly, God does not force Himself on us. He only moves as we yield to Him. Our insensitivity to the Holy Spirit limits His action in our life. We must learn to yield and cooperate with the Holy Spirit.

Things that quench the work of the Holy Spirit in our lives are matters of the heart, such as unbelief and rebellion. Sometimes an undue emphasis is placed on actions, leading people to believe that it's what we do that quenches the Holy Spirit. But our actions are only the results of our attitudes.

It is very likely that Paul's instructions in the next few verses about not despising prophecies (v. 20), proving all things (v. 21), and abstaining "from all appearance of evil" (v. 22), are some of the specific areas where the Thessalonians had been quenching the Spirit.