Quench not the spirit (το πνευμα μη σβεννυτε). Μη with the present imperative means to stop doing it or not to have the habit of doing it. It is a bold figure. Some of them were trying to put out the fire of the Holy Spirit, probably the special gifts of the Holy Spirit as verse 1. Thessalonians 5:20 means. But even so the exercise of these special gifts (1. Thessalonians 5:1; 2. Corinthians 12:2-4; Romans 12:6-9) was to be decently (ευσχημονως, 1. Thessalonians 4:12) and in order (κατα ταξιν, 1. Corinthians 14:40) and for edification (προς οικοδομην, 1. Corinthians 14:26). Today, as then, there are two extremes about spiritual gifts (cold indifference or wild excess). It is not hard to put out the fire of spiritual fervor and power.