Some crucial passages are: Deut 7:1-5; cf Ex 23:23ff; Deut 20:16-18.
Although our Lord did not explicitly endorse this particular act of judgement, as he did the destruction of Sodom and Gomorrah and of Noah’s contemporaries, he set his general seal on the book of Deuteronomy, which, from the number of times he quoted from it, must be regarded as his favourite book.
Specific endorsement is found in Acts 7:45; 13:17ff; Heb 11:31; 12:29. ‘Unquestionably the New Testament view is to take the Old Testament at its face value. It accepts the view that the whole world was lost in sin, without God and without hope. Not only was there no true knowledge of God, but the most debasing features of society found their focus in false religion. Idolatry went hand in hand with the blunting of perverting of all the highest human instincts, and became synonymous with lust and cruelty and the withering even of the natural affections. God’s purpose was to establish again a knowledge of himself in the earth. This involved the most relentless warfare with heathenism.’
‘It is difficult from the dry reports of the archaeologists to form any adequate human picture of the nature of the heathen cults. In view of the fact that the Israelite invasion did not lead to their eradication, much useful information as to their nature can be gleaned from the later periods of the history. The Old Testament directs its bitterest venom against Baalism and the cult of Molech. Baalism was a fertility cult, in which sexual licence was glorified as something religious and meritorious. There were “holy” prostitutes, male and female, for the gratification of the worshippers.” [According to G.E. Wright] “the amazing thing about the gods, as they were conceived in Canaan, is that they had no moral character whatsoever. In fact, their conduct was on a much lower level than that of society as a whole, if we can judge from ancient codes of law. Certainly the brutality of the mythology is far worse than anything else in the Near East at that time. Worship of these gods carried with it some of the most demoralising practices then in existence. Among them were child sacrifice, a practice long since discarded in Egypt and Babylonia, sacred prostitution, and snake-worship on a scale unknown among other peoples.”
‘It requires the disciplined skill of a historical novelist to convey to the imagination what such practices involve. Sholem Asch has used his skill to portray a Molech sacrifice in an imagined visit of our Lord to Tyre before the beginning of his ministry. Molech sacrifices were offered especially in connection with vows and solemn promises, and children were sacrificed as the harshest and most binding pledge of the sanctity of a promise. Even Greek writers were disgusted with this Phoenician practice, which became a prominent part of the religion of Carthage, and might well have overspread the world had Hannibal won the day in Italy. Sholem Asch portrays the hideous fascination of the rite, with its combination of solemnity and spectacle, of excitement and horror, or merry-making and obscenity, in which, as its central act, a young lad (no baby) is thrown into the red-hot arms of the god. Such practices could only prove a cancer in the life of any society, bringing a legacy of callousness and viciousness and fear, yet exercising a fascination which such a people’s bedased moral sense could not resist. A society nurtured in unwholesome excitement does not know how to live without it. It is not surprising that the Valley of Hinnon (Ge-henna), where Molech worship was practiced in the days of Manasseh, should have provided the Jewish image of hell.’
Wenham, The Goodness of God