Jamieson, Fausset and Brown on 1 Thessalonians 4:12

12. honestly--in the Old English sense, "becomingly," as becomes your Christian profession; not bringing discredit on it in the eyes of the outer world, as if Christianity led to sloth and poverty (Ro 13:13; 1Pe 2:12).

them ... without--outside the Christian Church (Mr 4:11).

have lack of nothing--not have to beg from others for the supply of your wants (compare Ep 4:28). So far from needing to beg from others, we ought to work and get the means of supplying the need of others. Freedom from pecuniary embarrassment is to be desired by the Christian on account of the liberty which it bestows.