There has been quite a lot of debate recently about the right tone to take when disagreeing with people misguided enough to deny evolution, or believe in pseudoscience or the supernatural. My own approach is to try to avoid engaging with them at all. I don't particularly want to be rude to such people, but I don't particularly want to be polite with them either. Life is too short to spend it arguing with people you are never going to agree with.
In these days of the 280-character tweet and the ten-posts-per-day blog, it's all too easy to get into a heated arguments with someone on the strength (or weakness) of a ill-considered online blurt. I've done it myself. Our modern means of communication encourage instant feedback, often to the detriment of thoughtful reflection.
Less so in Darwin's day. This from William Whewell in January, 1860:
My dear Mr Darwin
I have to thank you for a copy of your book on the 'Origin of Species'. You will easily believe that it has interested me very much, and probably you will not be surprized to be told that I cannot, yet at least, become a convert to your doctrines. But there is so much of thought and of fact in what you have written that it is not to be contradicted without careful selection of the ground and manner of the dissent, which I have not now time for. I must therefore content myself with thanking you for your kindness.
believe me | Yours very truly | W Whewell
This seems to me the right way to go about things. Whewell—a mathematician, historian and philosopher of science, who was also an Anglican priest and theologian—disagrees fundamentally with Darwin's revolutionary new theory, but is not prepared to dismiss it without more careful consideration.
I'm not sure how much careful consideration Whewell gave evolution by means of Natural Selection after his polite letter to Darwin. Not much, if their lack of subsequent correspondence is anything to go by. But at least Whewell had the decency to recognise that Darwin had provided a lot of food for thought: a position worthy of the gentleman who gave us the word scientist.