How long has God dealt with humanity and Israel on the basis of grace?
For the last 1900 and some years, God has dealt with the whole human race on the basis of His grace. That includes not only the Gentile but also the nation of Israel. This grace period follows the introduction of the gospel of grace, under which salvation is believing that Christ died and rose again, plus nothing.
Les explains that for the last 1900 and some years, God has been dealing with the whole human race—not just the Gentile, but even the nation of Israel—on the basis of His grace. He connects this to Romans 6, where God introduced the gospel of grace, so that Gentiles are no longer subject to the Judaic system or its legalism. Salvation is simply believing that Christ died and rose again, plus nothing, though believers are created unto good works and have the indwelling Holy Spirit.