The leading proponent of Modern Orthodoxy, Rabbi Professor Emanuel Rackman made the unity of the Jewish people his central theme, preferring to range people in a continuum of observance rather than divide them into rigid categories of — in American terms — Orthodox, Conservative and Reform.

In a 70-year career he was a congregational rabbi, university professor and, finally, president of Bar Ilan University in Ramat Gan, just north of Tel Aviv, dividing his time between Ramat Gan and New York.

At Bar Ilan, which he helped found in 1955 and enthusiastically fundraised for, he firmly maintained the underlying principle of Torah uMaddah, Torah and serious secular learning, which he had imbibed in New York’s religious educational system.

His Russian-born father, Rabbi David Rackman, was a senior member of New York’s rabbinical training college, RIETS (Rabbi Isaac Elchanan Theological Seminary), a division of the 19th century-founded Yeshiva University.

Like others of his generation, he had fled Tsarist Russia at the end of the 19th century to avoid conscription. With 25 years’ army service, Jewish recruits were usually lost to the community.

Among the many dodges available, David Rackman used the locally popular one of hunger-fasting to render himself medically unfit. However, as soon as the recruiters left and the hunger-fasters recovered, they had to leave quickly before word leaked out.

David Rackman left Slutzk in Byelorussia (Belarus) for the US, where he settled and married. Brought up in a religious and academic family, Emanuel was given responsibility early.

From the age of 10 he helped out his father, who had a speech impediment, by delivering his Torah lectures, the dvar Torah. It was a first-class grounding in public speaking.

Emanuel continued his dual education, combining higher Jewish studies with Columbia University law studies. A brilliant student, he gained semichah at RIETS in 1934, awarded by the pre-eminent rabbis Moshe Soleveichik and Dr Samuel Belkin. At the same time he gained advanced degrees in law and philosophy, although he had to wait till 1953 for his PhD in public law.

When he married Ruth Fishman in 1930, 18 rabbis stood under the chuppah. She died in 1997.

He practised law until volunteering for the US Air Force in 1943, when he became a chaplain with the rank of colonel. At the end of war, he advised on Jewish problems in the DP camps and later headed the Jewish chaplaincy body.

It was his experience of Holocaust victims that impelled him to stay in the rabbinic field. In 1946 he became rabbi of the Shaaray Tefila congregation of Far Rockaway, Queens, moving in 1967 to the prestigious Fifth Avenue Synagogue in Manhattan.

At the same time he continued his academic career, teaching political science at Yeshiva University, where he was provost from 1970-76, and Jewish Studies at CUNY, the City University of New York. In 1971 he became head of Jewish studies at CUNY.

He stood by his strong views on justice, undergoing a court martial in 1951 to vindicate his stance on the burning issues of the day around the Rosenberg spy trial and his support for the radical black singer, Paul Robeson.

His resistance to pressure resurfaced in the 1990s crisis on Jewish divorce, when he set up his own rabbinic court to try to help women get round the unequal treatment they were subject to.

In 1977 he became the fourth president, and first American president, of Bar Ilan University. Insisting on a true university ethos, he took a keen interest in students’ progress and their physical environment. In 1986 he became university chancellor and was made emeritus when he retired in 1999.

His core principle was Jewish unity. Dividing the community into hostile exclusive groups was anathema to him. “History has demonstrated that we all have the same fate,” he said.

He is survived by three sons, Michael, Bennett and Joseph; eight grandchildren and 14 great-grandchildren.