In context, Paul is writing a series of short commands to the church at Thessalonica on Christian conduct. Starting in 1 Thessalonians 5:16, he says, “Rejoice always, pray without ceasing, give thanks in all circumstances; for this is the will of God in Christ Jesus for you. Do not quench the Spirit. Do not despise prophecies, but test everything; hold fast what is good. Abstain from every form of evil.” The word quench means “to put out.” When you quench a fire, you put out the fire. When you quench your thirst, your thirst goes away. The word “spirit” here could refer to the Holy Spirit, or one’s own personal spirit. Either way, spirit is the source of all things spiritual. So the basic meaning of the command is not to put out the source of all things spiritual.
There are a couple of different ways that this could be interpreted. In the context, Paul tells them not to despise prophecies. Is Paul referring to the special gift of prophecy that many in the early church had? To the church at Corinth, Paul wrote, “Pursue love, and earnestly desire the spiritual gifts, especially that you may prophesy” (1 Corinthians 14:1). The church at Corinth was commanded to desire the spiritual gift of prophecy. If they did not desire such a spiritual gift, and then practice using it, they would effectively quench or put out the Holy Spirit’s ability to speak to them through this spiritual gift. It may be that this is what Paul has in mind about the church at Thessalonica as well. We should note that if this is the case, then this command would no longer apply to us today since we no longer have access to miraculous spiritual gifts as the church in the New Testament had access to them. It isn’t completely clear, however, that this is what Paul has in mind in 1 Thessalonians 5:19, though it may be.
Another way to understand this is that Paul may have been referring to the prophecies that were given in the Old Testament. Since Thessalonica had a synagogue, some may have had access to the Old Testament prophecies. We know that Paul and the other New Testament writers quoted heavily from the Old Testament. Knowledge of the Old Testament, and especially the Psalms and the book of Isaiah, was very helpful to the church. These prophecies were instrumental in teaching others the gospel of Jesus as was used by Apollos in Acts 18:24-25, and by Phillip in Acts 8:30-35. Not permitting the church to read and discuss the prophecies of the Old Testament would be effectively quenching the Holy Spirit’s ability to communicate with those teachings.
A third way that this verse could be understood is in terms of the fruit of the Spirit discussed in Galatians 5:22-23, “But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, self-control; against such things there is no law.” Christians are to be liberal in practicing the fruit of the Spirit in their lives. There is no law against practicing such things. So, what if we don’t practice these things in our lives? We have effectively quenched the Spirit by not living in this way.
Certainly, if we want to be spiritual people, then we must live in a spiritual way. This means listening to the message of the Spirit in the New Testament, and letting the fruit of the Spirit work within our lives without constraint. When we cut ourselves off from those spiritual sources of information and good works, then we have effectively quenched the Spirit in our lives.