"Open Orthodoxy", the Jewish movement which has been kicking up a storm in the US, has faced considerable opposition from the Modern Orthodox establishment there.
The term "Open Orthodoxy" was coined by Rabbi Avi Weiss, himself ordained as an Orthodox rabbi, who argues that "Orthodoxy" or Halakhic Judaism (i.e. faithful to Jewish law/Halakha) needed to be more "inclusive" and "flexible" to innovation than his contemporaries believed.
The movement has gained some traction in recent years, even as it is shunned by most other Orthodox rabbis, and has courted controversy by testing - and, as many respected rabbis insist, by outright crossing - the boundaries of Halakha.
Much of the criticism to the movement has come from the Rabbinical Council of America (RCA), the main body of American Modern Orthodox Rabbis and the largest rabbinic organization in the world.
One of Weiss's most vocal critics is Rabbi Steven Pruzansky, a former Vice-Chairman of the RCA and Arutz Sheva contributor.
Rabbi Pruzansky has written numerous articles opposing Open Orthodoxy, and insists that - contrary to the claims of its founder - it does not qualify as "Orthodox" at all, due to what he says is a complete abandonment of Torah values and a gradual abandonment of Halakha altogether.
Arutz Sheva sat down with Rabbi Pruzansky to get to the opposition to the Open Orthodox movement in the US.
Let's begin with the basics: why are you so vehemently opposed to the Open Orthodox movement?
"Whenever you qualify Orthodoxy with an adjective clearly you're trying to do something that is different and most often antithetical to the Torah, and I think that's the issue here.
"Anything that's 'open' has to eventually close, or has to be filled with something - and what they're trying to fill their movement with are ideas that are nothing new... they're actually very old, that's why I call it in my writings "neo-Conservatism", because they're going down a path that the Conservative Movement started a little over 100 years ago.
"It's not quite the same - it had to be updated for our era - but [the two movements are] almost identical in terms of the various issues: the integration of women in a public role in shul (synagogue); the more lenient and even lax standards when it comes to conversion; certain ideological departures that were very characteristic of the Conservative Movement as well."
"All of that might not be the official policy of Open Orthodoxy as a movement," Rabbi Pruzansky concedes, but he goes on to note how many leading members of the movement have embraced ideas "which are antithetical to the Torah," for example, by "denying the very authenticity of the Torah itself."
"One of their most prominent ordained rabbis has even argued that the Avot [Biblical Patriarchs] never really existed."
Positions such as these are what makes Open Orthodoxy "almost a replication of the road that the Conservative Movement took over 100 years ago", Rabbi Pruzansky reiterates.
"I think the public opposition to it is an effort to put up a roadblock, so they are not lost to the Torah world as was for the most part the Conservative Movement.
"What they [the Conservative Movement - ed.] tried to do was to 'modernize' the Torah; but what they ended up with was a diluted Torah that is indistinguishable from the secular value system of the western world."
Despite the bitter opposition to Rabbi Weiss's movement, Rabbi Pruzansky is careful to explain that the attacks are not personal.
"A lot of us have tremendous respect for the founders of Open Orthodoxy for all they've accomplished in the Jewish world," he says.
Rabbi Weiss was a leading activist in the fight to free Soviet Jewry, and has been an outspoken campaigner for the freedom of imprisoned Israeli agent Jonathan Pollard.
Instead, Rabbi Pruzansky compares the very vocal opposition to "putting up a big sign which says: 'Halt! You're going down a very dangerous road - don't take others with you like the Conservative Movement did!'"
You mentioned not "qualifying Orthodoxy" with adjectives, but what about Modern Orthodoxy?
"The term 'Modern Orthodoxy' is not a copyright title and even that requires definition.
"Every group tries to define itself differently, but I don't think that Modern Orthodoxy is an attempt to integrate secular values into Torah; rather, it represents a great appreciation or awareness of the Jew's place in the modern world.
"I don't think most Modern Orthodox Jews or rabbis for that matter would say that there is a parallel in importance between Torah values and secular values. Nobody [in the Modern Orthodox world - ed.] would argue that... I'm not sure that's the case in Open Orthodoxy."
He adds that the term "Modern Orthodox" is more "an attempt to distinguish it from hareidi-Orthodoxy, where involvement in the modern world is frowned upon or in some way 'unideal' on any level."
Where Modern Orthodoxy differs with hareidi streams of thought, he elaborates, is its belief that normative Halakhic standards can be strictly adhered to without shutting oneself off from the rest of the world. They are simply two different approaches, but share the same fundamental Torah values.
But despite all that, clearly there are many Jewish people who see Open Orthodoxy as filling a need... that something is missing in their Judaism. How do you respond to that?
For Rabbi Pruzansky, this question drills down to the fundamental error committed by movements such as Open Orthodoxy: an attempt to adapt and rewrite Torah values to suit every demand or ideal of the contemporary western world.
"You can't slake every thirst, that's the bottom line," he explains.
In particular, he says the domination of Open Orthodoxy and similar fringe movements by feminist activists is an indication that they are not drawing their fundamental values from the Torah, but looking outside of it.
"When it comes to feminism especially, it's a secular value, an un-Jewish value, and for the most part it's an anti-Torah value.
"When you mix something impure into a pure system, they don't go together... something will have to give... either the Torah or feminism."
He points out that he often meets Orthodox women who "see themselves as feminists in terms of the right to receive equal rights in the workplace and wages, etc... But not a single one is interested in wearing tefillin, being a hazan (cantor), because that's just a man's role in shul.
"The bottom line is that egalitarianism isn't a Torah value, so if you ask how it can fit with Torah - it's not going to be a natural fit!
"We need to be able to derive our values and our worldview from the Torah. Anything that's not there just isn't our values."
So is there perhaps a failure by the Orthodox leadership to communicate that message? Because clearly there are people seeking "Jewish values" from outside the Torah.
"Yes - there is actually double failure:
"The first failure is education - the notion (still entertained by many Orthodox educators) that everyone has to be educated the same way is fundamentally flawed.
"But there is a much broader point," he stresses, namely that "there are some Orthodox rabbis who have encouraged these expectations" because of pressure to cave into "secular values".
Like any legal system, he explains, "There is a limit to how much Halakha can tolerate."
"The failure to reach those expectations has engendered an industry of grievance; those grievances that are unassuagable are responsible for the creation of Open Orthodoxy and other fringe movements in the Torah world."
The phenomenon is helped along by the media, he says, which allows relatively fringe groups to punch well above their weight.
"They have the ear of the media so their influence is exaggerated.
"The Jewish media in America is by and large... hard-left, with very few exceptions, and even those with some connection to Orthodoxy - those with Orthodox publishers and the like - don't have appropriate respect for rabbis. Granted they thrive on controversy - that's also part of it - but they simply do not know or accept any limits.
"And that is also part of the problem: Western man does not accept any moral limits at all," he says, echoing the famous American saying: "Don't tread on me!"
In contrast, however, "Transposing that sentiment onto Torah is absurd.
"In Torah we surrender to the system, we don't conform the system to our desires."
So how is Orthodox world responding... how should it be responding?
"Right now we're in the realm of simply protesting.
"But there is a movement of thought that is gaining ground - it hasn't swept through all Orthodoxy - to actually ostracize and declare openly that these movements are not Orthodox - with all that entails for conversions, taking part in prayer quorums, etc...
Do you think that's the right route?
"I would much rather have some kind of rapprochement, reconciliation. The Torah world is small enough. It can accommodate the left-wing but it can't accommodate a female hazan, a female rabbi, dilution of conversion standards, mixed church choirs...
"There is only so much that the Torah world can accept; but nevertheless, rather than ostracizing or alienating I'd rather draw [them] near - but it has to be because we all accept he same terms of reference.
Do you think there is any hope for reconciliation at all?
"There's always hope. I'm not confident in the short term but in the long-term more so... except a number of adherents to this group will inevitably eventually leave Orthodoxy altogether.
"Even though it's not a large number of people they are still Jews and we want them part of the Torah world."
The reason for his optimism? "The mechitza" - the physical partition which separates between the men and women sections in Orthodox synagogues.
"The mechitza will naturally be a big stick in the craw of the feminists," he says, but an intruiging American legal precedent dating back to the 1950's means that the Orthodox "brand" is defined by the presence of a mechitza in shul.
Known as the Mt. Clemens case, it occurred when an Orthodox Jewish man named Baruch Litvin successfully sued his congregation for depriving him of his right to worship by introducing mixed seating.
The case means that "ironically, that which should be the first thing the feminists remove is actually the last thing."
So curiously enough, the decision as to which side of the Orthodox-non-Orthodox divide Open Orthodoxy falls into may rest upon it choosing which side of the fence, quite literally, its adherents sit.