Preaching to the unconverted: or how to convey science to the devout

It's said that charity begins at home. Likewise, a recent conversation I had with a pious Mormon started me thinking: just how do you promote science, both the method and the uncomfortable facts, to someone who has been raised to mistrust the discipline? Of course, there is a (hopefully) very small segment of the human race that will continue to ignore the evidence even after it is presented right in front of them, but stopping to consider those on the front line - such as biology teachers and ‘outed' atheists in the U.S. Bible Belt - how do you present a well-reasoned set of arguments to promote the theory and practice of science? 

It's relatively easy for the likes of Richard Dawkins to argue his case when he has large audiences of professionals or sympathetic listeners, but what is the best approach when endorsing science to a Biblical literalist on a one-to-one basis? The example above involved explaining just how we know the age of the Earth. Not being the first time I've been asked this, I was fully prepared to enlighten on the likes of uranium series dating, but not having to mention the 'D' words (Darwin or Dawkins) made this a relatively easy task. To aid any fans of science who might find themselves in a similar position I've put together a small toolkit of ideas, even if the conversation veers into that ultimate of controversial subjects, the evolution of the human race:

1. A possible starting point is to be diffident, explaining the limitations of science and dispelling the notion that it isn't the catalogue of sundry facts it is sometimes described as (for example, in Bill Bryson's A Short History of Nearly Everything). It is difficult but nonetheless profitable to explain the concept that once-accepted elements of scientific knowledge can ostensibly be surpassed by later theories, only to maintain usefulness on a special case basis. A good illustration of this is Newton's Law of Universal Gravitation, which explains the force of gravity but not what creates it. Einstein's General Theory of Relativity provides a solution but Newton's Law is much easier to use, being accurate enough to use even to guide spacecraft. And since General Relativity cannot be combined with quantum mechanics, there is probably another theory waiting to be discovered…somewhere. As British astrophysicist and populariser John Gribbin has often pointed out, elements at the cutting edge of physics are sometimes only describable via metaphor, there not being anything within human experience that can be used as a comparison. Indeed, no-one has ever observed a quark and in the early days of the theory some deemed it just a convenient mathematical model. As for string theory, it's as bizarre as many a creation myth (although you might not want to admit that bit).
2. Sometimes (as can be seen with Newton and gravity) the 'what' is known whilst the 'why' isn't. Even so, scientists can use the partial theories to extrapolate potential 'truths' or even exploit them via technology. Semi-conductors require quantum mechanics, a theory that no-one really understands. Indeed, no less a figure than Einstein refused to accept many of its implications.  There are many competing interpretations, some clearly more absurd than others, but that doesn't stop it being the most successful scientific theory ever, in terms of the correspondence between the equations and experimental data. So despite the uncertainty - or should that be Uncertainty (that's a pun, for the quantum mechanically-minded) - the theory is a cornerstone of modern physics.
3. As far as I know, the stereotype of scientists as wild-haired, lab-coated, dispassionate and unemotional beings may stem from the Cold War, when the development of the first civilisation-destroying weapons led many to point their fingers at the inventors rather than their political paymasters. Yet scientists can be as creative as artists. Einstein conducted thought experiments, often aiming for a child-like simplicity, in order to obtain results. The idea that logic alone makes a good scientist is clearly bunkum. Hunches and aesthetics can prove as pivotal as experimental data or equations.
4. Leading on from this, scientists are just as fallible as the rest of us. Famous examples range from Fred Hoyle's belief in the Steady State theory (and strangely, that the original Archaeopteryx fossils are fakes) through to the British scientific establishment's forty-year failure to recognise that the Piltdown Man finds were crude fakes. However, it isn't always as straightforward as these examples: Einstein's greatest blunder - the cosmological constant - was abandoned after the expansion of the universe was discovered, only for it to reappear in recent years as the result of dark energy. And of course mistakes can prove more useful than finding the correct answer the first time!
5. There are numerous examples of deeply religious scientists, from Kepler and Newton via Gregor Mendel, the founder of genetics, to the contemporary British particle physicist the Reverend John Polkinghorne. Unlike the good versus evil dichotomy promoted by Hollywood movies, it's rarely a case of us versus them.
6. Although there are searches for final theories such as the Grand Unified Theory of fundamental forces, one of the current aspects of science that differs profoundly from the attitudes of a century or so ago is that there is the possibility of never finding a final set of solutions. Indeed, a good experiment should generate as many new questions as it answers.
7. If you feel that you're doing well, you could explain how easy it is to be fooled by non-existent patterns and that our brains aren't really geared up for pure logic. It's quite easy to apparently alter statistics using left- or right-skewed graphs, or to use a logarithmic scale on one axis. In addition, we recognise correlations that just aren't there but we which we would like to think are true. In the case of my Mormon colleague he was entrenched in the notion of UFOs as alien spacecraft! At this point you could even conduct an experiment: make two drawings, one of a constellation and one of evenly-spaced dots, and ask them to identify which one is random. Chances are they will pick the latter. After all, every culture has seen pictures in the random placements of stars in the night sky (or the face of Jesus in a piece of toast).

Ursa Major (see what you like) vs evenly-spaced dots

So to sum up:

1. There's a fuzzy line at the cutting edge of physics and no-one understands what most of it means;
2. We've barely started answering fundamental questions, and there are probably countless more we don't even know to ask yet;
3. Science doesn't seek to provide comforting truths, only gain objective knowledge, but...
4. ...due to the way our brains function we can never remove all subjectivity from the method;
5. No one theory is the last word on a subject;
6. Prominent scientists easily make mistakes;
7. And most of all, science is a method for finding out about reality, not a collection of carved-in-stone facts.

So go out there and proselytise. I mean evangelise. Err...spread the word. Pass on the message. You get the picture: good luck!