en_tn/1co/14/39.md

do not forbid anyone from speaking in tongues

Paul makes it clear that speaking in tongues at a church gathering is permissible and acceptable.

But let all things be done decently and in order

Paul is stressing that church gatherings should be held in an orderly manner. AT: "But do all things decently and in order" or "But do everything in an orderly, appropriate way."