This paper discusses the impact of contemporary scientific knowledge on worldviews. The first three sections provide epistemological background for the arguments that follow. Sections 2 and 3 discuss the reliable part of science, specifically the characterization, scope and limits of the present scientific canon. Section 4 deals with the mode of thinking responsible for both the canon's credibility and its power to guide speculative activity. With these preliminaries in place, the remainder of the paper addresses the issue of tolerance to "alternative perspectives". The analyses in this part focus on the extent to which mature scientific thought embodies open-mindedness, with pluralism and competition between perspectives as central themes. I argue for four related claims, concerning scientific literacy, the impact of the canon on rational speculation, the limits of scientific pluralism, and the popular idea that recent forms of "scientific (natural) theology" have rational merit and can help worldview-making in our age, respectively: (C1) Which theories and narratives (or parts of them) belong in the scientific canon, and whether they are worldview independent, are matters contingent upon the state of knowledge--not something one can convincingly determine on metascientific or transcendental insight. (C2) The current scientific canon and its associated methodology provide research with strong directionality, often against popular currents. (C3) Current science does marginalize some views dear to many people. (C4) Although natural theology "officially" purports to embody scientific methodology, all it presently has on offer are poorly thought out ventures embodying (at best) only relaxed versions of that methodology; if so, the relationship between current projects in natural theology and science cannot (without begging the question) be reasonably described as one of "partial overlap", "mutual modification", or "ongoing complementarity".