Shared ground
Paul shifts into direct moral guidance by appealing to the Thessalonian believers “in the Lord Jesus.” The text’s explicit focus is everyday conduct (“how you ought to walk”) aimed at “pleasing God.” Paul treats this as something they already learned from him, not a new idea (explicit). He also assumes they are already living in that direction (“as you … walk”) while calling for increase (“abound more and more”) (explicit).
A second anchor is authority. Paul reminds them they already know the “charge” he gave, and he describes those instructions as given “through the Lord Jesus” (explicit). Whatever else is said about Paul, these verses present his ethical teaching as tied to Jesus’ authority rather than mere personal advice.
Where interpretation differs
These verses raise a real question about what Paul means by saying his appeal and instructions are “in/through the Lord Jesus.” Some read this as mainly relational language: Paul is speaking as a fellow believer, appealing on the basis of shared loyalty to Jesus. Others hear a stronger claim: Paul is reminding them that his moral instructions carry binding authority because they come with Jesus’ backing.
Another smaller difference concerns Paul’s tone in “as you … walk.” Some understand it as clear affirmation that they are successfully pleasing God already, and the “more and more” is about growth beyond a good start. Others read it more neutrally: Paul is describing the pattern they have, without strongly evaluating how well they are doing.
Why the disagreement exists
The wording can naturally carry more than one emphasis. “In the Lord Jesus” can signal shared identity, the sphere of Christian life, or an appeal made with the Lord’s authority. Likewise, “through the Lord Jesus” can mean “on the Lord’s behalf,” or “as teaching consistent with what the Lord requires,” without specifying the exact mechanism.
What this passage clearly contributes
This passage clearly links Christian moral instruction to three things: (1) a received tradition of teaching (“you received from us”), (2) a goal-language of conduct (“walk”) that is meant to please God, and (3) an authority claim connected to Jesus (“through the Lord Jesus”). It also frames the Christian life not as bare maintenance but as ongoing growth (“more and more”). The verses function as a doorway for the specific instructions that follow in 4:3 and beyond.