1 Corinthians 5:12

Paul’s authority as an apostle did not extend to judging and prescribing discipline on unbelievers for their sins. He did, of course, assess the condition of unbelievers (e.g., Romans 1; et al.), but that is not what is in view here. His ministry and the ministry of other Christians in judging and disciplining sin took place only within church life. Judging means more than criticizing. It involves disciplining, too, as the context shows.