All is not well in the Jewish state 50 years after its creation. Intended to protect the Jewish people from external attack, Israel is itself a house divided.

And quite apart from differences over the peace process or economic policy, one fundamental fault line is threatening to split Israeli society into two: that between the ultra-orthodox Jewish religious constituency on the one hand and the secular majority on the other.

As so often such short-hand terms obscure a multitude of degrees and shades of opinion. Many religious Israelis are tolerant of their less-religious fellow citizens. And only the most extreme in the secular camp want to remove all Jewish traces from the affairs of state.

But how Jewish should Israel as a country be? It is a debate that goes way beyond issues like civil marriage. In Israel there is no civil marriage as such - each religious denomination oversees its own ceremonies and procedures - which are then recognised by the state.

But the Jewishness of Israel is a complex issue. There is, for example, a significant non-Jewish minority. The only strand of Judaism recognized by the state - orthodox religious expression - is not the dominant strand in much of the Jewish diaspora, which inevitably provokes tensions.

But above all, the majority of Israelis who may be quite happy to have a Synagogue wedding - just as many Christians in European countries still get married in Church - resent being dictated to by what they see as the strident ultra-orthodox minority.

In large part the problem is an outgrowth of Israel's highly - some might say - over-representative political system. Here, ultra-orthodox political parties, many of whom do not accept the existence of the Jewish state are able to wield significant political influence.

Though these often unworldly people would argue that the creation of Israel is premature and should await the coming of a messianic age, they are quite happy to secure as large a share of state subsidies as they can for their religious institutions. And the mainstream parties of left and right seem unwilling to come together to limit the ultra-orthodox demands.

The religious status quo that has guided religious-secular relations since the creation of the State is under threat. Both sides say that their liberties are being encroached upon by the other.

But a secular backlash is developing. Many ordinary Israelis are increasingly fed up at seeing their taxes going to fund religious seminaries whose students avoid military service. They do not want to fund a parallel school system that prevents religious and secular children from mixing.

There are worrying danger signals; physical attacks for example on some ultra-orthodox Jews. It is this issue more than any other that will determine what sort of society Israel is to become. And it is one with which the mainstream politicians will ultimately have to grapple.