Forget words like "reformer" and "traditionalist". Ignore catchy labels such as "mods" and "rockers". As I listened to last week's Conservative Party Conference - in particular the speeches by the two men most often cited as "possible next leader", Michael Howard and Oliver Letwin - it became clear that there are two far more accurate and useful descriptions. Just as most Jews are either Orthodox or Reform, so Mr Howard and Mr Letwin are, if you like, Orthodox and Reform Conservatives.

It takes one to know one, perhaps. Although nominally an Orthodox Jew - I had my bar-mitzvah in an Orthodox synagogue - I am, intellectually, a Reform Jew. There is a bit of both in my Judaism. One Jewish friend even refers to me as Jew-ish.

Normally there is little reason why non-Jews should be in the least bit interested in the doctrinal differences within Judaism. But the parallels with today's Conservative Party are so striking - bear with me on this - that they do bear examination. As last week showed, the Tories excel at nothing better than endless debates about their future direction and who should be in charge - which of the many competing thinkers most cogently expresses what it means to be a Conservative today.

Both Michael Howard and Oliver Letwin are, as it happens, Jewish. But that is not the point. Whatever their personal beliefs - about which I neither know nor care - there are, in their attitudes to politics and to society, striking parallels with the two main strands of Judaism - Orthodox and Reform. And that division into Orthodox and Reform Conservative applies equally to the rest of the party, Jew and non-Jew alike.

Orthodox Jews are strict in their observance of the Torah (the scriptures). They believe in a literal Messiah, a literal restoration to the promised land, and a literal life after death. They are the Michael Howards of the Conservative Party. They remain unbending in their pure Thatcherism. They decry those who have not kept the faith and who seek to alter its tenets to adapt to modern times. Since their ideas are self-evidently right, it makes neither intellectual nor political sense to dilute those ideas. Those who do are, by definition, not proper Conservatives. Better, and more honourable, to be pure and in decline than to betray one's beliefs and purpose to court popularity.

The Reform movement arose when some Jews argued that Orthodoxy was untenable. They stopped striving to recapture a time long gone. The world, they argued, had changed. Instead of keeping strictly kosher, they saw that scientific and medical advances neutralised much of the original purpose of dietary laws. And instead of holding religious services in Hebrew, a language understood by a small minority, their rabbis spoke in native tongue, in words and phrases which connected with ordinary Jews.

They are the Oliver Letwins of today's Conservative Party - the "modernisers". Society has changed, and they see that it is up to the Conservative Party to adapt or die. Language which may have been appropriate in the 1980s misses the target completely today.

You certainly don't need to be Jewish to be Reform or Orthodox. Michael Portillo isn't, but he is a Reform Conservative, just as Norman Tebbit is Orthodox. And the labels apply beyond the Conservative Party: Tony Blair is Reform Labour and Gordon Brown, Orthodox.

The best guide to last week's events in Blackpool, and to politics more generally, is, it seems, not a political pundit but a rabbi.