It's on sale at Amazon and free on the internet archiveIf you're going to quote Luther, quote Luther, not propagandists quoting Luther. Luther said it, but your reference is partly bogus.
Rather than directly citing Luther, Father O'Hare cites "Amic. Discussion 1, 127." This refers to Jean François Marie Trévern, An Amicable Discussion on the Church of England and on the Reformation in General vol. 1. Various editions of this nineteenth century text are available online. I've had a copy of this book for over a decade. When it arrived all those years ago, I recall thumbing through it attempting to check O'Hare's references. I was never able to locate this O'Hare-cited Luther quote in An Amicable Discussion. Now with so many old books available on-line, I searched through a number of editions of An Amicable Discussion, and still could not find this quote as cited by O'Hare.