Further Note to make: Darwin did not discover "evolution", that species evolved was well known at the time, however it was believed to do so according to the
Lamarckian Paradigm, what he did discover was evolution occured via what he termed "natural selection", which had to do with animals adaption to their enviorments and that it took place over a very long period of time. It should perhaps be noted that the idea of historical "evolution" was hardly one which was invented by Darwin, the idea was perhaps the fundamental intellectual paradigm of the 19th Century: Hegelian Philosophy, Marxism (Diaclectical Materialism - Marx believed he had discovered social evolution like Darwin had discovered biological), Comtean Positivism... all these philosophies and many others at the time were evolutionary in their approach (though usually towards human history) and were developed before Darwin.
Similiarly, Darwin was not the first person to uncover that Earth was millions possibly billions of years old, that had been speculated for at least a century in geology (for example) if not alot longer, see
Georges Buffon and Sir Charles Lyell in the 1830s two and half decades before Darwin - though was a massive influence upon him - and his "Principles of Geology" argued that geological changes had taken place over ridiculously long time spans. In relation to Religion there was nothing in Darwin that wasn't in Lyell - except of course the nature of man, for who really cares about rocks?
Nor was Atheism uncommon in the 19th Century (anything but actually.. there were probably more hardcore or militant atheists at that time, then now), at least for someone of Darwin's class, education and profession.