Meaning
The Mosaic law (Num 5:11-31) prescribed that the suspected wife should be tried by the ordeal of the "water of jealousy." There is, however, no recorded instance of the application of this law. In subsequent times the Rabbis made various regulations with the view of discovering the guilty party, and of bringing about a divorce. It has been inferred from John 1:8-11 that this sin became very common during the age preceding the destruction of Jerusalem.
Idolatry, covetousness, and apostasy are spoken of as adultery spiritually (Jer 3:6, 8, 9; Ezek 16:32; Hos 1:2:3; Rev 2:22). An apostate church is an adulteress (Isa 1:21; Ezek 23:4, 7, 37), and the Jews are styled "an adulterous generation" (Matt 12:39). (Comp. Rev 12.)