Why is Israel's history hard to understand according to Les?
Israel's history is hard to understand because, despite all the manifestations of Jehovah's power, the people could sink into unbelief at the drop of a hat. Even the great prophet Elijah did so. The contrast between God's demonstrated power and Israel's quick unbelief is what makes the history difficult.
Les explains that this is what's hard to understand in all of Israel's history: in spite of all the manifestations of the power of their Jehovah God, yet at the drop of a hat, they could sink into unbelief. The context is Elijah's victory on Mount Carmel, where fire came down and consumed the sacrifice and licked up the water, proving Jehovah was still the God of Israel. Yet after Jezebel's threat, even this great man Elijah did sink into unbelief.