Are Israel and the church under the same system of law or grace?
Israel and the church are not under the same system. Israel is God's earthly people, predominantly under law, with Jerusalem as headquarters. The church is God's heavenly people, under grace, with heaven as headquarters. A chasm separates the two, so they cannot be mixed.
Les teaches that Scripture presents two distinct areas in which God works: the earthly people of Israel and the heavenly people, the Body of Christ. Israel was predominantly under law, and Jerusalem served as the headquarters of Judaism, with everything concerning the Jew funneling into and out of that city. By contrast, the church has no earthly headquarters; heaven is its headquarters. Les emphasizes that you cannot mix these two, because God's heavenly people are under grace, and a chasm keeps Israel and the church separated.