Humanism in its most virulent form tries to make science into a religion. It is awash with the intolerance of enthusiasm. For a start, there is the near-hysterical repudiation of religion. To quote Richard Dawkins:

"I think there's something very evil about faith … it justifies essentially anything. If you're taught in your holy book or by your priest that blasphemers should die or apostates should die – anybody who once believed in the religion and no longer does needs to be killed – that clearly is evil. And people don't have to justify it because it's their faith."

In the caricaturing of "faith" as murderous fundamentalism, one hears echoes of the bloody and interminable Reformation squabbles between Protestants and Catholics. It is also of course to give help to the real enemy, those who turn their back fully on science as they follow their religion.

There are other aspects of the new atheist movement that remind me of religion. One is the adulation by supporters and enthusiasts for the leaders of the movement: it is not just a matter of agreement or respect but also of a kind of worship. This certainly surrounds Dawkins, who is admittedly charismatic.

Freud describes a phenomenon that he calls "the narcissism of small differences", in which groups feud over distinctions that, to the outside, seem totally trivial. The new atheists show this phenomenon more than any group I have encountered.

This is a personal matter, so let me stress at once that I am not writing this from a sense of exclusion or hurt. I am happy with my position and I love a good fight. (If this piece has not convinced you of this, then nothing will.) Dawkins has said that on a scale from zero to seven, from belief to non-belief, he scores about 6.9. I am even a tad higher than that. I am a true non-believer. I am also a fanatical Darwinian – more so even than Dawkins, because I think that when it comes to culture, genes do much that he hands over to his own special cultural notion of "memes". I have written many books about the implications of Darwinian thinking for epistemology and ethics.

What's more, I think that religion has done and continues to do much harm to society. In the blog I write for the Chronicle of Higher Education I have taken on the Catholics, the Calvinists, the Mormons (that got me into hot water), and even the dear old Quakers (perhaps a bit Oedipal, because I was raised a Quaker). I was the expert witness in philosophy in Arkansas when the American Civil Liberties Union successfully fought against a law requiring the teaching of so-called "creation science" (aka biblical literalism) in the publicly supported schools of that state. I have been a vocal opponent of creationism for many years.

And yet I, and others like me, am reviled in terms far harsher than those kept for real opponents like creationists. We are labelled "accommodationists" for our willingness to give religion a space not occupied by science. We are put down in terms that denote strong emotion, way beyond reason. In The God Delusion, I am likened to Neville Chamberlain, the pusillanimous appeaser of Hitler. Jerry Coyne, author of both the book and the blog Why Evolution is True and an ardent groupie of Dawkins and Christopher Hitchens, wrote about one of my books in terms used by George Orwell: "There are some ideas so absurd that only an intellectual could believe them."

The Minnesota biologist PZ Myers, who writes the blog Pharyngula, has referred to me as a "clueless gobshite". And if I had a dollar for everyone who has made a pun out of my last name, I would be a very rich man. Because I will not toe the line absolutely, because I will not bow down in praise of Dawkins and company, because I laugh at their pretentions and positions, I am anathema maranatha.

As I said, I don't care about the personal attacks. I have the kind of personality that welcomes being in the public eye, even if the attention is critical. I have teased Coyne and sent him $50 as a retainer to make sure I am not forgotten. But I do think it all tells us something. Call it a secular religion if you will, but the humanism I have been discussing in this piece does bear strong similarities to conventional religion. One finds the enthusiasm of the true believer. And as a non-believing Darwinian evolutionist, as one who is a humanist in the broader sense, this makes me feel rather ill.

• A longer version of this article appears in Aeon magazine