Why is there no evidence in seforim that neither the neviim such as Ovadya, Yehu, Michayahu, etc. nor Yehoshafat himself, demanded that Ahav allow the people to go to Yerushalayim and destroy Dan and Beis El as part of his teshuva/humbling himself to Hash-m? Why would they even associate with Ahav under these circumstances?
David Goldman, USA
You ask why they would even associate with Achav under these circumstances? Indeed, Yehoshafat was punished for doing so. According to the Medrash, he was destined to die, and his life was spared only because he cried out to Hash-m.
As for Achav's Teshuvah, you yourself write that it took the form of humbling himself before Hash-m. He did so when he heard of the impending destruction of his entire family. That in itself, may well have been sincere. However, there is no indication that he showed the least remorse for the Avodah-Zarah which he had and still was, worshipping. His Teshuvah it appears, was not complete. It was a passing phase, and that is why Hash-m forgave him only temporarily, destroying his family one generation later. As a matter of fact, he died exactly the same horrible death that Hash-m had initially decreed.
In view of what we just wrote, it is hardly surprising that Yehoshafat and the prophets did not succeed (we don't know what efforts they made in that direction) in getting Achav to abolish the idols in Beis-Eil and Dan, any more that all the prophets throughout the era of the first Beis-Hamikdash succeeded in doing so.
Be'Virchas Kol Tuv
Eliezer Chrysler