Perhaps, but then again, they do belong to the Council of Islamic Nations among other bodies based solely on their religion. And they do want to blow up Israel. They are jihadists in their own way. Granted it's a significantly different way from most, but that doesn't make them any less behind the concept of Islam ascendant over all humanity.
Besides, the rest of the jihadists hate them for the creation of a clergy class, something which does not exist in classical Islam. It's a matter of religious interpretation and not one of discordant external interest.
Well, the Commonwealth is a council of English-speaking and generally English-culture nations, but no one accuses them of trying to impose Englishness on the world. The OIC (I'm assuming that's what you're
referring to) is, from what I understand, not really that big a deal among the member states and secondly, Iran's membership makes them no more or less threatening than any other member (say, Albania).
The fact is that Ahmadinejad might talk big, but he's not in charge. And the people in charge, in an ironic twist, are the mullahs, but they are also much more pragmatic. The ruling elites, like in any country, are the business, governemtnt, media and military elites, who have no interest in gambling away Iran's substantial power on some religious whim. They may wear robes, but they understand perfectly well that if a government and nation wish to be successful, deciding policy based on religious fundamentalism is not the way to go. I would liken them to the Chinese ruling officials during the 1980s: their foremost goal is to be powerful, and ideology takes a back-seat to that. I can't say I'm particularly knowledegable, obviously, but I have made some minimal effort to read whatever I can find on Iran (in additon to having two Iranian friends), and I think that just as China may be socialist in name but capitalist in reality, so Iran is religious in name and for show, but pragmatic and technocratic in reality. Iran is no more likely to declare war on the West in the name of Islam than China is likely to declare war on the West in the name of socialism (which obviously, at this point, is a virtual impossibility).