Jeremiah 9:26

Egypt, and Judah, and Edom, and the children of Ammon, and Moab, the Jews with all the nations surrounding them, and all that are in the utmost corners, that dwell in the wilderness, literally, "all having their hair," that is, their beard, "clipped at the corners," a custom in use among the heathen nations, but expressly forbidden to the Israelites, Leviticus 19:27; Leviticus 21:5; for all these nations are uncircumcised, they had not accepted the rite by which the Jews were distinguished as the chosen people of the Lord under the covenant made with the patriarchs, and all the house of Israel are uncircumcised in the heart, that is, in their case the outward observance of the formerly significant rite had lost its meaning, since they had not turned to the Lord in true repentance. Without such change of heart the rite of acceptance into the outward membership in Israel was of no avail, just as the Sacrament of Baptism has no value in the case of those who do not believe. A mere outward observance of the customs of religion will not bring men to true fellowship with the Lord.