What used to be an overwhelming consensus in favor of the Neo-Darwinian view has shrunk to the point where it seems the only thing holding it up is the lack of any plausible naturalistic alternative.
There has always been dissent from the standard neo-Darwinian model among creationists of various stripes, of course, as well as intelligent design theorists (Some ID theorists are creationists, but many are not. ID is not the same thing as creationism), but, as Dierker notes, "...the growing discontent in academia is from secular naturalists."
Benjamin Dierker writes about this eroding consensus in a piece at The Federalist. Here's an excerpt of the heart of his essay:
While Christians have long challenged Charles Darwin’s theory of undirected evolution, few appreciate the true extent of the challenge beyond the church. Current estimates are that approximately one-third of professional academic biologists who do not believe in intelligent design find Darwin’s theory is inadequate to describe all of the complexity in biology.There's more at the link. When students hear that there's no doubt among biologists that the Darwinian explanation of life is at least a close approximation of the truth, when their teachers or the media tell them that there's no controversy among scientists about the basic truth of Darwinian paradigm, students should be more than a little skeptical.
A controversial letter to Nature in 2014 signaled the mounting concern, however slow and cautious, among thoughtful professional biologists. Other works by atheist authors like “What Darwin Got Wrong” and “Mind and Cosmos” find “fatal flaws” in the theory and assert it is “almost certainly false.”
The important note is that these are not ideologues or religious zealots, nor do they propose a god or biblical solution. Rather, they find problems with the explanatory value of Darwin’s theory in light of modern understanding of mutation, variation, DNA sequencing, and more. These expressions of doubt do not reject naturalism or evolution per se, but the rigor of the Neo-Darwinian model for explaining the development of life.
In fact, they want to help Darwin, not tear him down. That he needs help is news to the academy.
The leading critics have been intelligent design supporters, who are looked down on by naturalists. But as each group adds to the scientific literature, certain critiques and findings inevitably bolster or redirect the research of the other.
The effects go at least one way. Following work and theories of Stephen Jay Gould, Michael Denton helped shape a generation of skeptics with his 1985 book “Evolution: A Theory in Crisis.” An evolutionist and agnostic, Denton has continued his criticism.
In the past decade, the works of professor Michael Behe, Steven Meyer, and others have given more life to the debate on the national stage. In “Darwin Devolves,” Behe points to the process of mutations to describe the inadequacy of an unguided materialist process to add information. Meyer explores the Cambrian explosion and the complexity of the cell to show the biodiversity and complexity we observe, and notes that natural processes have never been observed to produce such results.
Importantly, these two men, and many others, believe in the standard multibillion-year timeline for the Earth and make their findings based on deduction of natural evidence rather than starting from authority in scripture or elsewhere. The growth of the intelligent design community is noteworthy, but not as interesting as those who are apart from it, secular, and nonetheless find Darwinian evolution to contain serious flaws.
Behe explained that, “Based on conversations with my own colleagues at Lehigh [University], dozens of other biologists, and news stories in journals I would guesstimate that a third or more of biologists are quite skeptical that Darwin’s theory explains all of biology.” The growing literature speaks for itself.
What most commenters mean when they give these sorts of assurances today is that some naturalistic explanation, whether Darwinism or something else, must be true. The discerning student, however, will recognize this as an assertion of metaphysical faith, not a scientific claim. It simply reflects the speaker's philosophical commitment to naturalism.
Unfortunately, too many people who make such pronouncements dress them up in a white lab coat and give the impression that naturalism has been scientifically proven - a feat, were it possible, would be the most spectacular accomplishment in the history of science.