Darwin described him self as an Agnostic. From Wikipedia. In his...

Darwin described him self as an Agnostic.

From Wikipedia.

In his 1871 book The Descent of Man Darwin clearly saw religion and "moral qualities" as being important evolved human social characteristics. Darwin's frequent pairing of "Belief in God" and religion with topics on superstitions and fetishism throughout the book can also be interpreted as indicating how much truth he assigned to the former.
In the introduction Darwin wrote:
"Ignorance more frequently begets confidence than does knowledge: it is those who know little, and not those who know much, who so positively assert that this or that problem will never be solved by science."