Whether the children of the Northern Tribes had forgotten God on accident or on purpose, the result has been the same: apostasy. Eliyahu (Elijah) had an uphill battle trying to reintroduce God to the children of Israel.
Ahab had a soft-spot for evil, both physical (Ben-Hadad) and spiritual (Yezebel). But as we read later on, Ahab started to learn that God is above him.