"The real reason why Paul was devoted to the doctrine of justification by faith was not that it made possible the Gentile mission, but rather that it was true. Paul was not devoted to the doctrine of justification by faith because of the Gentile mission; he was devoted to the Gentile mission because of the doctrine of justification by faith."
J. Gresham Machen, quoted in Peter Stuhlmacher, Revisiting Paul's Doctrine of Justification: A Challenge to the New Perspective, page 90.
Our justification by grace alone through faith alone in Christ alone apart from all our works creates huge allowances for creativity and adaptation in ministry, so that we can bring the gospel to more and more unlikely people.
Who couldn't give his life to this?