Circumcise yourselves. All the Jews had been circumcised in the flesh, but not all had been circumcised “to the Lord.” The prophet sought to reveal the real meaning of the rite and to counteract a merely formal, ritualistic conception of it. Circumcision was intended to be a symbol of the devotion of the heart to God and a mark of separation from idolatry (see on Gen. 17:10, 11). To remove the foreskin of the heart meant to put away all impurity (see Deut. 10:16; 30:6). True circumcision is inward rather than outward (see Rom. 2:28, 29; Phil. 3:3; Col. 2:11).
None can quench it. The prophet likened God’s anger against sin to unquenchable fire, that is, fire that no one could extinguish until it had completed its work of destruction (see ch. 7:20).