Passage
quench not the Spirit;
quench not the Spirit;
1 Thessalonians 5:17 pray unceasingly;
1 Thessalonians 5:18 in everything give thanks, for this is [the] will of God in Christ Jesus towards you;
1 Thessalonians 5:19 quench not the Spirit;
1 Thessalonians 5:20 do not lightly esteem prophecies;
1 Thessalonians 5:21 but prove all things, hold fast the right;
The verse centers on "Spirit" and "quench". It is saying that the verse draws attention to "Spirit" and "quench", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 18's "in everything give thanks for this is..." into verse 20's "do not lightly esteem prophecies...", so "Spirit" and "quench" belong inside that flow. In 1 Thessalonians context, the local focus is Christ, faith, and discipleship.
A plain takeaway is to answer the verse's own emphasis on "Spirit" and "quench" with trust shaped by these words, not by a vague optimism outside the passage.