According to the "wall of separation" between church and state which is implicitly extant in the first amendment of the Constitution--or so say the imaginative hermeneutics of our courts--espousing one's own religious convictions while in the employ of the state is strictly forbidden. After all, if a single individual who is employed by the state expresses a particular religious view is that not equivalent to "Congress passing a law respecting an establishment of religion"? I think we can all see clearly that this is precisely what the founding fathers meant to protect against.
I'm being facetious, of course. There is no such "wall of separation" in the Constitution--just as there is no "right to privacy" guaranteeing abortion on demand--and not even the most convoluted, inventive interpretive lens can get you there. Only a brazen act of willful defiance of the text combined with some creative fiction could ever reach such a conclusion. At least such an initial act is required to get where we are today, though presently you also have so many years of legal precedents--based on that initial fiction--which serve to fortify it.
And, OK, perhaps stating any religious opinion isn't strictly forbidden, but suffice to say that, for instance, a Christian professor at a public university has to tread very carefully when it comes to speaking some of his most strongly held religious views, whereas an ardent, zealous, evangelically secular professor need not fret in the least.
If the establishment clause is taken to mean that individuals employed by the government are not to make any religious declarations whatsoever while carrying out their official secular duties as educators, should this not also extend to pronouncements of irreligion? Should not this imagined "wall of separation", if we are going to acknowledge and respect it, also mean that preachings of unbelief be similarly forbidden? If the "wall" is hard, fast, and sturdy should it not drown out all the external chattering of belief and unbelief alike?
Yet you'd be hard pressed to find any examples of professors at public universities being chastised for extolling the virtues of secularism or denouncing the evils of religion. While instances of professors being scolded, or even fired, for "preaching" or for "spewing hate speech" are (or at least were) quite numerous, and are on a rapid decline only because everyone knows the score.
Evangelical secularism is rampant and unchecked in our public institutions, thanks largely to a few malignant acts of judicial malpractice, and their perpetuation. It should go without saying, but the role of justices in our system is to adjudicate. For the Supreme Court this often entails entering pretty murky waters where vague and imprecise language abounds, to be sure. Nevertheless, while vague language can often have multiple possible meanings, depending on the perspective and the chosen interpretive framework of the reader, this does not mean that it can have any meaning.
If we are to assume a default, neutral position in our roles as public educators, why is it recklessly assumed that a secular stance is a good default? The neutral position on the question of religion is not secularism; secularism is one extreme on the spectrum of ideas concerning the subject of religion. Our institutions themselves are secular, yes, but not the people who populate them. And that is the distinction that needs to be drawn; individuals working for the state are still individuals, not the state itself, and they have no constitutional obligation to feign neutrality on matters of religion--should they arise--or to keep their pieties private. There are plenty nefarious cultural and social influences which serve to bolster the nasty idea that religion should be a strictly private matter, we don't need official U.S. law worsening the matter.
Alas, of course, there is not much practical to be done on this count. It's not as if there were a single existing law I could point to that I would like to repeal. There are decades of legal precedents that need to be wiped clean, or amendments to the Constitution that need to be passed to counteract them in order to undo the damage. Neither of those remedies constitutes a small task in the least. Though, in the former case, if the wails of despair from the left over Citizens United are to be taken seriously, perhaps this isn't as difficult as I imagine it to be.
But there's an alternative, less radical solution, which I have hinted at. Namely: we keep our scandalous and false reading of the Constitution much the same as it has been to date, only we apply similar restraints on those proclamations of irreligion and unbelief as we do to religious opinions. Atheism is a strictly religious idea (or non-idea); it's the idea that all religions are false, and thus there is a wall of separation between atheism and the American secular state, as counterintuitive as this may seem. This is only a 'solution' in that it remedies an existent inequity; it doesn't address the initial judicial malpractice. It only makes consistent the application of that 'interpretation' of the Constitution which we have chosen to adopt. That's a start, anyway.
I don't mean to insinuate that the vast majority of professors at public universities are consciously going out of their way to spread atheistic, secularist doctrine. Certainly the vast majority of physics, mathematics and English professors throughout the country carry out their jobs without often having the cause or opportunity to share whatever their personal convictions on these subjects happen to be. In the liberal arts and humanities departments, however, you're sure to see a steep incline in this type of thing, though often in subtle forms, or in the guise of 'simply relaying facts'. And then some smaller percentage of the time you'll find the more egregious, overt manifestations of the kind of thing that I'm objecting to. How prevalent it happens to be is besides the point though; if a "wall of separation" exists, then it exists between the state and all religious positions, including anti-religious sentiments.