Judaism has at last caught up with itself. In the first century, it was a pluralist faith (although they would never have used that word), with a plethora of Jewish sects – Pharisees, Sadducees, Therapeutae, Essenes and Nazarenes – all practising their own versions of Judaism.
The war with Rome and subsequent exile resulted in a massive upheaval, after which only one group, the Pharisees, survived. They dominated Jewish life for the next 18 centuries, developing what came to be known as Rabbinic Judaism, and later as Orthodoxy.
It was only on 17 July 1810 – some 200 years ago last week – that this monolithic form of Judaism was shattered. Reform Judaism was founded in Germany, and an attempt made to revitalise a faith that, in the eyes of many, had become stagnant.
This in turn led to other Jewish groups emerging – liberals, conservatives and reconstructionists – with Judaism returning to the diversity of former times and Jews today having much greater choice on how to express their faith.
How would you know if you were entering an Orthodox or Reform synagogue? Your eyes would tell immediately. In an Orthodox synagogue, men and women would be seated separately (as a sign of their different roles), whereas in a Reform one they would be seated together (indicating their full religious equality). Moreover, in the latter, the rabbi might well be female.
Your ears would also sense the difference. In an Orthodox synagogue, only Hebrew would ring out, whereas in a Reform one there would be prayers in the vernacular too, a way of blending a sense of biblical roots with the reality that the linguistic home of British Jews is English.
Closer inspection of the liturgy would reveal that, although many prayers used by the Orthodox and Reform were entirely the same, some had been changed to reflect a new Jewish theology. Reform, for instance, no longer prays for the restoration of animal sacrifices or for a return of the exiles to the land of Israel – historically very important, but religiously no longer appropriate.
Reform has also changed passages about the physical resurrection of the dead to a spiritual afterlife. Similarly, references to the messiah have been altered to "the messianic age", emphasising that what is important is the era of harmony that will occur, not the person who helps achieve it.
Just as a significant is the major redefinition of key components within Judaism. The rabbi was once a person characterised by his scholarship, and not necessarily involved in everyday communal life or in leading prayers. Now he or she has been transformed into a pastoral figure, immersed in congregational issues, whose work revolves around birth, bar mitzvah, betrothal and burial, as well visiting the sick and taking services.
The notion of the synagogue has also changed remarkably: it's no longer just a place of worship but a communal centre, with parent and toddler groups, film evenings and adult education, ensuring that it is not just for religious Jews but also those who are agnostic or even atheist, but who still see themselves as Jewish.
To borrow a phrase from another faith, Judaism is now a "house with many rooms" (John 14.2). It is significant that a rabbi is familiar with that quotation, and that he is prepared to use it in public.
This epitomises the revolution that has been ushered in by Reform Judaism, catering for Jews no longer isolated from the rest of society or fearful of surrounding culture, but thoroughly engaged with it and harmonising ancient roots with modern realities.
(c) Jonathan Romain, a rabbi in Reform Judaism, is minister of Maidenhead Synagogue . He is the author of Jews of England  and Reform Judaism and Modernity: A Reader , and has recently edited Really Useful Prayers . Dr Romain is also chair of the Accord Coalition  for the reform of faith schools - of which Ekklesia is also a co-founder and corporate member.
This article is adapted with permission from Jonathan Romain's regular Guardian newspaper column .