[1] Zvi Yehuda Kook was born on the eve of Passover[9] in 1891 in Zaumel in the Kovno Governorate of the Russian Empire (now Žeimelis in Northern Lithuania), where his father served as rabbi and was a prominent local Zionist.

[9] His mother was his father's second wife, Reiza Rivka, the niece of Eliyahu David Rabinowitz-Teomim, Chief Rabbi of Jerusalem together with Shmuel Salant.

There Kook studied Talmud under the guidance of Rabbi Reuven Gotfreud, the son-in-law of Yoel Moshe Salomon,[a] one of the founders of Petah Tikva.

[b] His father, until his dying day, was to remain Kook's principal teacher, though at this time he hired a private tutor to teach his son Russian.

[9][d] It has been claimed he contributed to the preface on halakha (Jewish law) regarding the heter mechirah (sale permit) for the Sabbatical year[e] attached to his father's work Shabbat Haaretz, which was published in 1910.

After several weeks in a detention camp in Hamburg, he was released and allowed to return to Halberstadt, where he needed to report once every two days in the local office.

Only the following year, at the end of 1915, was he granted permission to leave Germany and join his father, who was stranded in St. Gallen, Switzerland,[17] due to the war.

[22] In the mid-sixties, its standing rapidly improved as a result of frustrations encountered among elite graduates of Bnei Akiva when their attempts to exert influence in the National Religious Party were met with a rebuff.

Thereafter, this group, which constituted a secretive fraternity called Gahelet[g][h] (including such rabbinical figures as Eliezer Waldman, Moshe Levinger and Haim Druckman) shifted their attentions towards Kook and his yeshiva.

[22] After the Six-Day War in 1967, of which he has been called 'the ultimate theologian,'[23] he induced the Israeli government to approve the building of settlements in the West Bank and Gaza and sent his students to that mission.

His remarks were elliptical in their allusive references to rabbinical traditions many of his followers were unfamiliar with, and his authority rested more on his charismatic figure – charisma was something his father stressed – than his writings.

The Kooks' innovation consisting in elaborating a theology that bridged the gap between a faith that saw Zionism as a heresy, and the Zionist programme for the development of a secular state for Jews.

"[27] Zvi Kook, together with Harlap, was heir to a tradition of messianic demonizing thought going back at least to Judah Alkalai, in which the redemption of Jews in Israel was a premise for, and precursor to, the general uplifting of mankind.

[25] In Kook's vision, Jews were unique, the yardstick for mankind, with Judaism forming the core of humanity and reality itself, and Israel analogized to the soul while the world at large was likened to the body.

[31][l]In this context, Zvi Kook extended the ideas of his father[m] and his fellow student of kabbalah Harlap, who had an outlook of hostility to Gentiles and asserted that the failure of the peoples of the world to surrender to Israel would cause their downfall.

Kook took this Jewish nationalism as in fact cosmopolitan, in the sense that the redemption of the world was contingent on Israel, an idea that proved influential with the early Hapoel HaMizrachi thinkers.

"[35][36][o] According to his disciple, rabbi Eliyahu Avichail, who founded the immigrant organization Amishav in 1975, Kook himself advised him to search for dispersed communities of Jews who had lost contact with their roots, prepare them for conversion (giyur) and facilitate their "return" to Israel.

Though initially considered a "crackpot", Avichail succeeded, after conferring on these peoples the ethnonym Bnei Menashe, in having some two thousand relocated in Israel, especially in the Israeli settlement near the Palestinian city of Hebron, namely Kiryat Arba, through financial assistance from his philanthropical sponsor Irving Moskowitz.

Rummaging through two millennia of sources uncritically, such as Toledot Yeshu, he revived a tradition of anti-Christian polemics which, according to some critics,[41] had not seen the likes for over a millennium.

[43] His writings on this theme circulate among Israeli settlers, or Torah purists aspiring to a life of secluded study and, conversely, among anti-semites.

[47] Sometimes among his acolytes called the "prophet of Greater Israel",[48] Kook's father had taught that settlement of the land should come about by peaceful means, not by war.

[26]The teachings of Zvi Kook are considered to be the source for the ongoing tension among Israeli settlers between the idea that the state of Israel is sacred, and doubts whether its secular authority could be exercised independently,[54] Initially, Zvi Kook had expressed unreserved support for Zionism, and was fiercely opposed to orthodox critics of that ideology,[55] seeing Zionism as a vehicle embodying God's will for the redemption of the Jews.

[56] Even before the Six Days War Kook expressed concern for Jewish Biblical sites in the adjacent West Bank under Jordanian rule.

On the eve of the outbreak of hostilities he shocked his students by speaking of the "truncated" state of the Land of Israel, inducing in them a sense that they had sinned in forgetting about places like Hebron, Shechem and Jericho.

[59] At a 1974 lecture delivered at Merkaz Haraz in the presence of Moshe Dayan, he stated that moves to yield the Golan, and the West Bank would lead to a war, one that would be fought "over our bodies and limbs".

The Gush Emunim movement predominantly formed by religious Zionists soon came under the dominating influence of graduates from Mercaz HaRav driven by a messianic activism to thwart territorial compromises.

These ideas, if acted on, would constitute in Kook's view treason and would cover Israel with "eternal shame"[62] Though Kook disapproved of religious coercion in Israel,[63] he argued that the rabbinical concept of peace, shalom reflected a state of absolute justice, which required at times the force of coercion, and did not entail, as in the modern assumption, an implicit renunciation in principle of recourse to violence.