I summarized for you some parts of Charles Darwin own view on religion - the full statement (a part of his biography) is at this site: http://www.update.uu.se/~fbendz/library/cd_relig.htm
Another good site for you to look at is this wiki site that summarizes his views periodically.
http://en.wikipedia.org/wiki/Charles_Darwin%27s_views_on_religion
I had gradually come to see that the Old Testament from its manifestly false history of the world, with the Tower of Babel, the rainbow at sign, etc., etc., and from its attributing to God the feelings of a revengeful tyrant, was no more to be trusted than the sacred books of the Hindus, or the beliefs of any barbarian. The question then continually rose before my mind and would not be banished, -- is it credible that if God were now to make a revelation to the Hindus, would he permit it to be connected with the belief in Vishnu, Siva, &c, as Christianity is connected with the Old Testament. This appeared to me utterly incredible.
I gradually came to disbelieve in Christianity as a divine revelation. The fact that many false religions have spread over large portions of the earth like wild-fire had some weight on me.
Beautiful as is the morality of the New Testament, it can hardly be denied that its perfection depends in part on the interpretation which we now put on metaphors and allegories.
But I was very unwilling to give up my belief, but I found it more and more difficult, with free scope given to my imagination, to invent evidence which would suffice to convince me. Thus disbelief crept over me at very slow rate, but was at last complete.
Everyone who believes, as I do, that all the corporeal and mental organs (excepting those which are neither advantageous or disadvantageous to the possessor) of all beings have been developed through natural selection, or the survival of the fittest, together with use or habit, will admit that these organs have formed so that their possessors may compete successfully with other beings, and thus increase in number. Now an animal may be led to pursue that course of action which is the most beneficial to the species by suffering, such as pain, hunger, thirst, and fear, -- or by pleasure, as in eating and drinking and in the propagation of the species, &c. or by both means combined, as in the search for food. But pain or suffering of any kind, if long continued, causes depression and lessens the power of action; yet is well adapted to make a creature guard itself against any great or sudden evil. Pleasurable sensations, on the other hand, may be long continued without any depressive effect; on the contrary they stimulate the whole system to increase action. Hence it has come to pass that most or all sentiment beings have been developed in such a manner through natural selection that pleasurable sensations serve as their habitual guides. We see this in the pleasure from exertion, even occasionally from great exertion of the body or mind, -- in the pleasure of our daily meals and especially in the pleasure derived from sociability and from loving our families. The sum of such pleasures as these, which are habitual or frequently recurrent, give, as I can hardly doubt, to most beings an excess of happiness over misery, although many occasionally suffer much. Such suffering is quite compatible with the belief in Natural Selection, which is not perfect in its action, but tends only to render each species as successful as possible in the battle for life with other species, in wonderfully complex and changing circumstances.
That there is much suffering in his world no one disputes. Some have attempted to explain this in reference to man by imagining that it serves for his moral improvement. But the number of men in the world is as nothing compared with that of all other sentiment beings, and these often suffer greatly without any moral improvement. A being so powerful and so full of knowledge as a God who could create the universe, is to our finite minds omnipotent and omniscient, and it revolts our understanding to suppose that his benevolence is not unbounded, for what advantage can there be in the suffering of millions of the lower animals throughout almost endless time? This very old argument from the existence of suffering against the existence of an intelligent first cause seems to me a strong one; whereas, as just remarked, the presence of much suffering agrees well with the view that all organic beings have been developed through variation and natural selection.
Another source of conviction in the existence of God connected with the reason and not the feelings impresses me as having much more weight. This follows from the extreme difficulty or rather impossibility of conceiving this immense and wonderful universe, including man with his capability of looking far backwards and far into futurity, as the result of blind chance or necessity. When thus reflecting I feel compelled to look at a first cause having an intelligent mind in some degree analogous to that of man; and I deserve to be called a theist.
This conclusion was strong in my mind about the time, as far I can remember, when I wrote the Origin of species; and it is since that time that it has very gradually with many fluctuations become weaker. But then arises the doubt -- can the mind of man, which has, as I fully believe, been developed from a mind as low as the possessed by the lowest animal, be trusted when it draws such a grand conclusions? May not these be the result of the connection between cause and effect which strikes us as a necessary one, but probably depends merely on inherited experience? Nor must we overlook the probability of the constant inculcation in a belief in God on the minds of children producing so strong and perhaps an inherited effect on their brains not yet fully developed, that it would be as difficult for them to throw off their belief in God, as for a monkey to throw off its instinctive fear and hatred of a snake.
I cannot pretend to throw the least light on such abstruse problems. The mystery of the beginning of all things is insoluble to us; and I for one must be content to remain an Agnostic.