that you may walk properly toward those who are outside, and may have need of nothing.
Toward them that are without ...  Paul was concerned that the Thessalonians have a good reputation among the non-Christian population, a goal which should be of concern to Christians of all generations.  A good reputation of the saved for minding their own business and conducting holy and blameless lives not only made them more acceptable to their pagan compatriots, but also commended the gospel to persons not yet obedient to it.