"Leaving Truth" offers a radically new, and potentially conclusive, contribution to our ancient science vs. religion debate. It is a collection of five essays, one main and four subsidiary. The collection addresses how we can most coherently select proposals as knowledge, and the limitation from this on the kinds of proposals that we can select. Though at first glance abstruse and academic, addressing this most basic epistemic question seems to yield a very surprising result: That we have been maintaining our concept "truth" either redundantly or as an independent and reason-antithetical basis for knowledge; and that the proposals of all of our authoritarian systems of emotionally seductive irrationality -- in particular, but not limited to, our theistic religions -- can only be maintained from this basis. "Leaving Truth" suggests that our past 250 years of progress in epistemology can be summarized through the injunction that we should stop asking of any knowledge proposal, "Is this 'true'?" and start asking instead, "Can I honestly qualify this as knowledge?" It then shows how and why our theists cannot do this for their proposals. Its logical core demonstrates that both of the modern epistemological developments that are broadly assumed by theists and atheists alike to support the theists' position (David Hume's dismissal of Induction as our basis for "objective proof", and Karl Popper's demonstration that science can provide only "best present" knowledge, as opposed to certainty) achieve instead the opposite. That they undercut the theists' position at a level from which no coherent defense can be made. Leaving Truth thereby offers atheists and free-thinkers a prospect for the kind clear victory at the intellectual and academic level that we have not dared to hope for since collapse of the Radical Enlightenment.