stands. In contrast to those who wander away (v. 18).
seal. An expression of ownership and security.
The Lord knows those who are his. A quotation of Num. 16:5 (according to the Septuagint translation). Inscribed on the people of God is His eternal decree of election (v. 11), which ensures the security of the body of Christ (John 10:29).
Let everyone . . . depart. Also inscribed on the membership of God’s church is His call to holiness (v. 21), including the repudiation of false teaching.