ISIL is a rather more militant than average subset of the overwhelmingly most populist subset of Islam, the religion of about 1.5 billion people, including the overwhelming proportion of our neighbours ands friends in Indonesia, Malaysia, India and Pakistan. In somewhat the same manner that Catholic followers of Opus Dei believe that super-identification with the words of their prophet is the sine qua non of being a Christian, the inner circle of ISIL followers have come to believe that one cannot be a true disciple unless one has stoned a adulteress to death.

Millions of observant Sunni Muslims, without such an extremist, absolutest and false view of what is commanded, give a certain grudging support to ISIL, because it represents what they see to be the truth as against an apostate faith such as Shia Islam, or because it is Muslim rather than Christian or Jewish, or because ISIL is of the book, and not pagan and non-Semitic.

The problem for political, diplomatic and military types trying to prevail in such thickets of religious belief, unbelief, consensus, misunderstanding and common culture is in guessing where people will be a decade or two hence. It's very confusing, at the moment. ISIL, in its Syrian rebel form, is more or less who we support against President Assad of Syria.

By and large, we prefer their close allies, the less extremist, less jihadist and less pan-Arabic partners in the revolt against President Assad of Syria, which have, one way or another, and directly or indirectly, been getting millions from the western world, as well as Sunni followers. Just over the border, in Iraq, is our sworn enemy, a challenge to everything we stand for.

Allowing that we would prefer more moderate opponents of Assad, ISIL is still about the best organised, and most reliable of the groups we could call our own. But, that's only as far as Syria itself is concerned.

As it turns out, ISIL is the greatest single threat to the unlikely possibility that the people of Iraq, whether of Shia, Sunni or Kurdish background will ever again, post Saddam Hussein, meld into an artificial nation based on lines drawn upon a map by British and French manipulators of about 100 years ago. Is there any longer much hope that common interest could again draw together people of Sunni, Shia, Kurdish, Christian and Jewish descent around a common artificial geographic backdrop? And if geography is no guide, nor is common history, whether in Syria or Lebanon, or both. Redrawing the boundaries has become almost inevitable, as has been the likelihood that the consequent problems will spill over into Turkey and Iraq. If Australia has any influence - doubtful other than from the diaspora - we would be better involved in ultimate solutions than in helping bat out for a draw.

ISIL is, apparently, an extra special menace to Middle Eastern, or western civilisation, because it thinks that the natural way of joining people together might be on the basis of common religions, or tribes, or backgrounds, rather than lines drawn on a blank page British and French imperialists 100 years ago. There is, thus, an area of Mesopotamia, loosely called Iraq, and of Syria and Lebanon, that leans, historically, doctrinely, and tribally towards Istanbul. There's another which points towards Damascus, Baghdad and the doctrines and icons of the direct descendants of Mohammed.

There's another, more northern part, in the same nations, that is ethically different, and which, with fellow Kurdish parts of Turkey and Iran, yearns for autonomy and independence. To the north east of these parts is ancient Persia, which leans towards Damascus, and, to the south and the west, and, as it turns out, the east and the extreme west are nations which are irredeemably focused on Mecca and Istanbul and who regard the religion based at Damascus as idolatrous and wicked.

ISIL, by itself, is regarded by the west, and by the Shia, as an irredeemably extremist subset of the conventional majority followers of the majority Sunni sects. But it could not exist without strong financial support from supposedly mainstream Muslims in Saudi Arabia, the Gulf States, Yemen and Afghanistan, and from groups within Pakistan, Malaysia, Indonesia, the Sudan and Nigeria, and even in Britain, Australia, Canada and the United States. ISIL is not unlike the Provisional IRA in the 1980s - technically disapproved of, particularly for overt violence and extremism; in fact tacitly supported, if at no cost other than small sums of money, particularly in the more romantic Irish diaspora.

We have created a dialogue in Australia about the hundreds of overt, and thousands of silent supporters of ISIL. It is a threat, here and abroad. But it is more likely to be diluted by having its general ideals absorbed into a mainstream than by explicit repudiation by conventional followers of Sunni. Many ordinary Sunni, after all, wonder whether they do enough to bear witness to their religion, just as many Christians do.,

Right now, Australia politicians are working themselves into agonies of indignation about ISIL extremism, indeed about how much even the conventional al-Qaeda movement has repudiated them for going too far. ISIL panders to this idea by boasting about atrocities performed on people it regards as apostates. To its own followers, however, its fundamentalism and zeal is focused at showing how much it is defending a Sunni mainstream against backsliders. ISIL collects millions, by the week, from ordinary Sunnis and rich Sunni families, in Saudi Arabia, the Gulf States, Yemen, Africa and eastern Asia, and even in western countries, including Australia.

When westerners, including Australians, were silly enough to invade Afghanistan, for the umpteenth unsuccessful time, 11 years ago, modern sober westerners remarked that the contradictions in the intensely local and tribal Afghani body politic would be resolved only by deals in which old "enemies'' joined with current goodies, and many current goodies were cast out. Peace would arrive only when the Taliban was part of the deal.

Likewise with Syria and Iraq. In such artificial nations, peace is an idea, not a reality. It is possible only when a bigger coalition of people holding power, whether by tribe, cult, religion, region or ethnicity, outnumber those against their solutions. Even then, coalitions are temporal, and things tend to fall apart, particularly when those playing one side against another forget about the significance of tribe, culture or geography in the way power is distributed.

During Australia's entirely failed and wasted mission to Afghanistan it was known by almost all of the Australians out in harm's way that many of those we treated as "enemies" would be present at the ultimate peace table. Naturally enough some of our most bitter enemies would prove to be our best friends, and vice versa.

Is there anything more dispiriting in trying to get troops enthused for battle? Put another way, do Australians understand that not a thing we did, nor a life we lost, nor a VC won, made the slightest difference in the ultimate outcome of Afghani politics?

A decade hence, no Afghanis will even remember that Australians were there. Nothing we did will have lasted long enough to make the faintest ultimate difference to outcomes. Is this - was this - a fair return for the $3 billion we spent there, to no effect whatever, or the young men whose lives were lost?

It's much the same with Syria. One does not have to waste much time rehearsing the supposed wickedness of ISIL, or the threat it poses to the peace.

If, or when, there is a peace, ISIL will have to be part of the deal, probably in the government of both of the old, or, certainly, the new, nations involved. At that point, if Australia is involved, ISIL will have to be part of the solution. At that point, we, if not ASIO, may well think it among the most reasonable of the parties involved.

That's if, of course. These days we do not matter a bit, other than as sources of spare blood. There was a time when Australians made a difference. It was Australians (and not, despite the history books, Arabs led by Lawrence of Arabia) who conquered Damascus, for the first time by westerners in 1000 years in 1918. And it was Australians, (not as the history books pretend, Free French) who did it again 23 years later. In such days our force, if not our ideas, counted for something. Not any more.