Ezekiel 23:37
That they have committed adultery, and blood is in their hands, and with their idols have they committed adultery, and have also caused their sons, whom they bare unto me, to pass for them through the fire, to devour them. That they have committed adultery, and blood is in their hands, and with their idols have they committed adultery, and have also caused their sons, whom they bare unto me, to pass for them through the fire, to devour them.
The verse presents Israel and Judah under the figure of lewd, adulterous women, and the corrupt woman stands for a corrupt church. The searching moral instruction lies in that figure, exposing the awful sins of Judah and Israel with application predicting the last days. Some passages around it are fit to be read anywhere, but this verse itself is best read in private.
The adultery is spiritual unfaithfulness, meaning idolatry and apostasy from the worship of Jehovah through forsaking God and abandoning His covenant. Seeking help in Egypt instead of God was part of that fornication and was rebellion against Him. Turning to foreign powers and idols meant abandoning the covenant with God for the ways of Babylon and the nations. The blood in their hands and causing sons to pass through the fire to devour them were literal bloodshed and sacrifice of children to idols as part of that unfaithfulness, practiced despite God's prohibition. Babylon's spiritual fornication means departing from God's law and worship to join idolatrous or false religious groups, not merely complying with civil laws for temporal affairs.
In the chapter's setting, Babylon's attack, the loss of Israel's kingdom, and the scattering of Israel came as judgment following disobedience to God. The same guilt rests on professed Christian churches that seek union with the civil power. God has furnished fullness of blessing in Jesus Christ and demands all from His church, and He will not divide His glory with another. The prohibition against those idolatrous practices is just as binding today as ever, because God changes not, so what was abomination to Him in any former time is abomination still and ever will be.