Why did Israel turn to pagan gods when they had proof of the living God?
Israel turned to pagan gods because the human race has an innate bent to worship false gods, a tendency present since the Tower of Babel. Despite having proof of the living God from their beginning and knowing better, they followed after idols, as seen in Jeremiah 44 and the Mount Carmel controversy.
Les explains that this tendency has plagued the human race since at least the Tower of Babel: there is an innate bent in human nature to worship a false god, idols of one sort or another. Even Israel, who had the proof of the living God all the way back from their beginning and should have known better, followed after pagan gods. Jeremiah 44 is his example, and he recalls Elijah's controversy on Mount Carmel with the prophets of Baal, whom Israel had been following.
But since we left off to burn incense to the queen of heaven, and to pour out drink offerings unto her, we have wanted all things, and have been consumed by the sword and by the famine.