However, where Dr Habash is a secular Christian who leads the Marxist Popular Front for the Liberation of Palestine (PFLP), Fathi Shkaki is the general secretary or operations chief of the Islamic Jihad Movement in Palestine, which has practised revolutionary Islam - in some of the most deadly attacks on Israelis during the five-year intifada.
From Palestinian Islamic Jihad's inception in the 1980s, the Israelis understood its danger. 'In 1983,' Dr Shkaki said, 'when I was under interrogation, they told me I was very dangerous, because I combined religion with nationalism.' Dr Shkaki has a cheerful manner and gentle courtesy expressed in flawless English. Born in 1951 in Rafah camp, in the Gaza Strip, he studied medicine in Egypt, where he came under the influence of the Gamaat al-Islameya groups. In 1979, his book Khomeini, the Islamic Solution and the Alternative sold 10,000 copies in two days. He returned in 1981. Arrested by the Israelis in 1983, released in 1984, re-arrested in 1986, he was exiled to Lebanon in 1988. He went to Tehran, and met Ayatollah Khomeini. The next year he came to Damascus.
Dr Shkaki was open about both aims and means. 'Jihad' in Arabic means struggle. The PLO's Abu Jihad ('father of struggle'), killed by Israelis in 1988, co-ordinated the intifada from Tunis. But in an Islamic context, jihad covers a range of activity from spiritual self-improvement to holy war. 'Our aim is to liberate Palestine from the (Jordan) river to the (Mediterranean) sea. It is the place where all religions can live together. Armed struggle is still the main means. Because we believe that Israel was built up by violence. We cannot deal with UN resolutions. Our cause is just.'
They had to strike now. 'Any time from 1948 till now is the right time. We don't need to be strong enough. This is our land. We know that our struggle will not liberate Palestine tomorrow or after tomorrow. But that does not prevent us starting our struggle.'
He described differences with the Islamic Majamma movement of Sheikh Ahmed Yassin, which grew into Hamas, the Islamic Resistance Movement. Associated with the Muslim Brothers, its main issue was Islam. Islamic Jihad's main aim is Palestine. Sheikh Yassin had originally preached against direct confrontation. He said Palestinian Muslims were not strong enough to depend on themselves alone. He aimed to educate Arab and Islamic countries so that the Islamic community would liberate Palestine. Dr Shkaki was different: 'We do not interfere in the affairs of those governments.'
Recently, Hamas has moved to far more military-style confrontations with Israeli forces. Dr Shkaki described the myriad Palestinian groups which invoked the Islamic call. It was untrue, he said, that Islamic Jihad had ever been a branch of Fatah, the PLO faction led by Yasser Arafat. He understood the confusion. In 1985 - two years before the intifada, but when Islamic activity in Gaza was fervid - 'some brothers in Fatah contacted us and told us they want to leave Fatah for Islamic Jihad. They were Abu Hassan Qassem and Hamdi Tamimi, killed by a car bomb in Cyprus in 1988. We asked them to form a military committee, which was known as Saraya (brigades) of Islamic Jihad.'
Dr Shkaki claimed major military operations. He crowed over the fact that last Friday, his 'brothers' had waged a nine-hour gun battle in Jenin, on the West Bank, killing an Israeli officer. The incident which claimed most Israeli lives during the intifada was in July 1989, when a Palestinian grabbed the wheel of a bus travelling from Tel Aviv to Jerusalem and sent it plunging into the ravine. 'One of our brothers killed 17 of them in the bus.'
Was this not terrorism, killing civilians? 'We never attack Israelis outside Palestine. Resistance is maintained against those who occupy our land. When we talk to our brothers inside Palestine we make priorities. First, the Israeli army. Second, the settlers. The Israelis are fighting. They kill every day, women, old men, children. Then it is legitimate to kill any Israeli so long as they do the same. We do not give specific orders.'
He said most of his 'brothers' were in what he called the occupied land. But he acknowledged political and material support from Iran, and co-operation with Hizbollah in southern Lebanon.