Joshua charged them with an oath at that time, saying, Cursed be the man before Yahweh, that rises up and builds this city Jericho: with the loss of his firstborn shall he lay the foundation of it, and with the loss of his youngest son shall he set up the gates of it.
One result of moral filth is physical disease. Therefore, the destruction of the Canaanites (in some cases together with their sheep and cattle) ensured the removal of deadly diseases that could have threatened Israel’s existence. The absence of Canaanite religious practices would also be a help to Israel’s religious life and moral well-being.