I hope you caught the irony in that. The fact is that religious- or worldview-neutrality is impossible, because any system of laws and public policies will inevitably reflect some people's worldview assumptions over those of others. Ethics is nothing other than applied worldviews, and civil law is nothing other than publicly applied social ethics. So long as there are multiple worldviews represented by those who live in the society (which will be the case in any society that contains more than a handful of people), the law will reflect some views and reject others. Secularism (in the sense discussed here) is nothing other than the establishment of Agnosticism/Atheism as the official religion of the society, to the exclusion of other worldviews (other worldviews may be tolerated to some extent, but only at the sufferance of the values of the established worldview).
This basic argument for the impossibility of religious neutrality in civil law has been made lots of times and by many different kinds of people, though it has failed to gain a strong foothold in the general American psyche at least partly because the entire American project of "religious equality" is rooted in the idea of religious neutrality. To admit that the latter is impossible is to give up on the mainstream idea of the former and thus to give up on something that is seen to be a part of America's core, unique identity.
Below I have provided links to an array of articles making the argument against the possibility of neutrality. The articles represent the thinking of very different people with very different worldviews but who are united in having come to admit that neutrality is impossible and in their choice to speak out about that fact. These articles can provide a place to dive in for those who wish to think about this issue with greater depth.
First of all, one the best mainstream academic authors I have come across in the modern day who points out the impossibility of neutrality is Steven D. Smith. Smith is a University of San Diego law professor.
Here is a list of his books on amazon.com. They are all excellent.
Here is an excellent article he has written entitled "The Paralyzing Paradox of Religious Neutrality."
Here is another one entitled "Blooming Confusion: Madison's Mixed Legacy."
Here are some more great articles on this subject:
Is Secularism Unprincipled? - by Ian Polluck. Polluck is an Atheist, but one who recognizes the inherent hypocrisy of the secular project so often favored by modern American Atheists (though he advocates for it anyway even while recognizing its hypocrisy).
Down with Secularism! - by Richard Smyth, another Atheist who recognizes the non-neutrality of secularism.
Is God Unconstitutional? - by Phillip E. Johnson of Intelligent Design fame. Johnson provides a very perceptive analysis of modern popular, legal, and academic cultures and how they are influenced by Naturalism (Agnosticism/Atheism) despite their claims to be worldview-neutral. His book Reason in the Balance is a fantastic work along these lines as well.
I'll also add a few articles I have written related to the subject:
The Impossibility of Neutrality
The Impossibility of Governmental Neutrality in Religious Matters
God's Law, Civil Law, and Liberty of Conscience in Catholic Doctrine
Steven D. Smith on "Smuggling"
The basic point, well put by an Atheist (Richard Smyth, from the article linked to above):
Let’s take another look at that liberal phobia about “imposing your views on others” (and let’s leave aside that “imposing”: apart from being freighted with the symbolism of jackbootery, it’s not really important in this argument – whether and how things are “imposed” is a question of government practice, not policy).
Perhaps the argument here is that a gay marriage or an abortion, say, is in some sense a personal matter, and nobody else’s business. If so, it’s an argument that crumbles as soon as you spin it around and take a look at it from the other side. If I believe that human life is sacred, then an abortion is essentially a murder. A woman has no more right to terminate her foetus than a mother has a right to strangle her three-year-old son. And a person who believes this has a moral obligation to prevent it wherever possible. The same goes for a person who believes that human society is being irreparably damaged by buggery and opiates (or whatever) – and the same goes, too, for a government.
It is deeply dismaying that so many liberals struggle with this basic empathetic step.Published on the feast of St. Catherine of Siena