Why does God deal with Israel nationally most of the time?
God deals with Israel nationally most of the time because the covenants were made with the nation, not merely individuals. The national level is where the covenant promises operate, even though individual Jews can still be saved. Israel's national spiritual condition is blindness, but that does not prevent individual salvation.
Les explains that Scripture shows God dealing with Israel on two levels: national and personal. Most of the time He deals with them nationally because that is where the covenants come in—the covenants are with the nation. An individual Israelite can still be saved today, but nationally the Jew is blind. The parable of the lost coin illustrates this: Israel as a nation was God's by covenant promises, yet lost, and the one lost is the one He brings to Himself, just as with the lost sheep. Les also notes that the prodigal son account includes the older brother, whom preachers often ignore, but he maintains that brother fits when the passage is kept in its proper context.