Sean Carroll shares his Edge World Question Center post on Dysteleological Physicalism. The crux is that the world cannot be explained in terms of design or purpose, but in terms of things and rules - so that what happens today relies on the state that existed before it started happening, so to speak.
The comments are an excellent read - and engender this train of thought:
We are creatures that are fortunate to have consciousness - the ability to be aware of ourselves. Our mental subsystems are a) the ability to reason; b) emotion; c) motor impulses such as the fight-or-flight response.
Science, in this view, is the triumph of the reasoning layer of our consciousness - an ordering of observations on the way the world appears to work, with a high (but not absolute) certainty, based on experimentation, observation and refinement. These observations may be modified or discarded as new information becomes available.
Religion, in this view, is the triumph of layers b) and c) in explaining the world, due to a deficit of a). Thousands of years ago, this world view was all that humans could achieve, since the struggle to subsist made the time available to examine the world in a systematic way a low priority; the tools and concepts to do this in a meaningful way had not been invented yet; and the tools to record, share and modify the observations and interpretations in an efficient way were millennia away.
Now that we have hundreds of years of experimentation and observation under our belts, and we have better systems of reasoning about the observations, and better systems to communicate about them, the old ways of explaining the world should be discarded. That is not to say that universal truths should be discarded along with them - the Golden Rule exists in all cultures, and predates organized religion. It has stood the test of time, and will continue to do so.
Those who can reason, should.