Saeed Jalili, who replaced Ali Larijani as Iran's top nuclear negotiator at the weekend, is a man of strong moral views who believes spiritual values must inform political actions.
His absolute conviction of the rightness of Iran's cause, and his loyalty to his old friend Iran's hardline president, Mahmoud Ahmadinejad, may make him an awkward interlocutor when talks with the EU on the nuclear dossier resume in Rome tomorrow.
In a lengthy interview conducted in Tehran last year, Dr Jalili, then a deputy foreign minister, offered a robust worldview that simultaneously revealed a lack of understanding and experience of the west largely typical of the Ahmadinejad government. Although his official brief covered Europe and North America, he has spent little or no time there.
Dr Jalili's views on the nuclear issue reflected this odd mixture of moral certainty and political disingenuousness bordering on naivety.
"We have announced time and again that we believe in the logic of negotiation. But at the same time we will never give in to the logic of intimidation and threats," he said.
"Two issues or components have to be considered. One is the concerns of the Europeans; the other is the inalienable rights of the Iranian nation."
Iran was not seeking the bomb, he said: it should be remembered that Iranians had been the victims of weapons of mass destruction, supplied by the west to Saddam Hussein during the Iran-Iraq war.
"Even during that war, we never entertained the idea of using such weapons ourselves," he said. "We believe they are illegal and inhuman. We believe the real might of any country relates to the relationship between the people and their government. After years of isolation, this country continues to stand tall. It is because this relationship exists here."
Dr Jalili said Iran had already gone much further, in terms of a previous two-year suspension of its enrichment research and additional inspections, than it was obliged to do under the nuclear non-proliferation treaty (NPT).
"Basically, what we are dealing with here is nuclear apartheid: some countries have rights and others are told they do not have similar rights ... I also believe our insistence on our position helps maintain the spirit of the NPT."
Dr Jalili described Mr Ahmadinejad as an "old friend of mine" whose principal offence, in the eyes of the US and Britain, was to speak truth to the world.
The president's political philosophy began and ended with Islam, he said. He was leading a "big debate" about how to reinsert justice and spirituality into political life.
He defended Mr Ahmadinejad's controversial threats against Israel. "He is saying that the state of Israel will fade away if the democratic process is observed [a reference to Iran's official view that all Palestinians, including those living in exile, should be given a vote], and they will only have themselves to blame."
There were no difficulties over Judaism inside Iran, he claimed, pointing to the presence of a Jewish MP in Iran's parliament and a 25,000-strong Jewish community nationwide. The problem lay instead with Israel and with a "small group of people imposing their views" on the rest of the world. "It is time the international community did something about this."
The peddling of conspiracy theories and other intolerant, fundamentalist thinking is nothing unusual in Iran. One newspaper this weekend labelled France's president, Nicolas Sarkozy, a "Zionist henchman" for his warnings about Tehran's nuclear activities.
Dr Jalili's unexpected elevation to the supreme national security council may afford him a significant position from which to promote his views. But the conclusion of many western analysts that his appointment marks a major advance for the Ahmadinejad faction in Iran's divided government may prove simplistic.
The move coincides with changes in other key portfolios, including the oil and industry ministries and, possibly, foreign affairs. Mr Ahmadinejad is under withering fire over his failure to grow the economy, petrol rationing, and so far unsuccessful privatisation measures. Even conservative MPs have criticised Dr Jalili's inexperience. There is evidence, meanwhile, that UN- and US-orchestrated financial sanctions are biting.
All this appears to indicate uncertainty about nuclear policy, growing unease over Iran's international position, and a resulting, accelerating power struggle in ruling circles as the possibility of a reformist-pragmatist comeback in parliamentary elections next March looms large.
Dr Jalili's advance is but one move on a much bigger board. And the fact that the displaced Dr Larijani will still attend the Rome talks, as the personal representative of the supreme leader, suggests the struggle is growing ever more intense.