Here's Weikart's summary of his essay:
So, what lessons can we draw about the relationship between religion and evolutionary theory from Darwin's own trajectory? First, as he developed his evolutionary theory, he moved from Christian belief in a personal God to a deistic position to agnosticism. It is not clear to what extent his religious views shaped his evolutionary theory, or vice-versa. It seems reasonable to think they developed in tandem.Agnosticism is in fact atheism. An atheist is one who lacks a belief in God, and, since agnostics lack such a belief, they're atheists. The difference between an agnostic and an atheist like, say, Richard Dawkins, is that the Dawkins type atheist (What I call a "hard" atheist) asserts flatly that God does not exist or most probably does not exist. The agnostic, like Darwin, (what I call a "soft" atheist) does not make such a strong claim, but says that although God may indeed exist, there's not enough evidence to warrant believing that He does.
Second, he rejected any divine intervention or even divine purpose in his evolutionary scheme. Third, he rejected the religious basis for morality. None of these points is good news for those trying to refashion Darwin into a religious believer whose evolutionary theory is no threat to religion, especially to traditional forms of Christianity.
The only substantive difference between the hard and soft atheist is that, theoretically if not in actual practice, the soft atheist is more open to, and less dismissive of, theism than is the hard atheist.