In context, Paul was referencing those who feel the need to be more outward focused which could involve things like ceremonial requirements, avoiding certain foods, esteeming one day to be observed above other days, etc., whereas someone who has grown further into the freedom and grace found in Christ is potentially more focused on trusting in the blood of Jesus and the redemptive work He performed, once for all.
Paul exhorted them not to judge but to receive one another in the same way God shows us peace and patience.

