According to the recent Pew survey of American Jews, only a quarter still believe in the God of the Bible (26 per cent), compared with almost twice as many who profess belief in a “higher power” (50 per cent). Although a similar question has not been put to British Jews, when the 2013 Institute for Jewish Policy Research survey asked people what values were important to their Jewish identity, only just over half cited belief in God (52 per cent).

A significant number of Jews in the West seem no longer to believe in a personal Deity, the bedrock of classical Judaism.

As Rabbi Arthur Green writes in his new collection of essays, Judaism for the World, which won a 2020 National Jewish Book Award in the USA, conventional notions of faith “have failed to speak to so many” and insistence on literal belief has driven many away.

For the better part of six decades he has tried to address this spiritual vacuum through the evolution of a neo-Chasidic outlook. A pioneer in the countercultural chavurah movement in the United States in the 1960s, he founded a non-denominational rabbinic training academy, Hebrew College in Boston, in 2004.

From the 19th century, Western Judaism largely settled for a respectable rationalism with little time for the wilder flights of the mystics. Green instead turns back to the mystical tradition, adapting ideas from Kabbalah and Chasidut to fashion his contemporary approach for “seekers”.

Rabbi Green understands God not as separate from the universe but as the “mysterious oneness of being” that unites all forms of existence and is present within each unique form: for reasons beyond our grasp, it “Big Banged itself into the endless dance of variety and multiplicity” within a dynamic process of creation, the whole “mysteriously and infinitely greater than the sum of its parts”.

The Kabbalists saw the figure of God in the Bible as a projection emerging out of the divine Infinite, the Ein Sof, in order to reach out to the finite minds of human beings. Green turns the idea on its head, seeing the biblical God as a human projection born of a need to try to comprehend the ineffable.

The task of religion, he says, is the “cultivation of an awareness that we live in relation to the transcendent, something larger than ourselves”.

He acknowledges that his is an “abstract” theology, but his Judaism is rooted in concrete observance. He believes in the discipline of regular practice and ritual as a way to evoke in us a sense of “awesome presence”. But he is less concerned with halachic minutiae than the kavannah, the intention, behind the act. Indeed, he rejects the idea of Torah as a legal system rather than as a body of teaching to help us make the “leap of consciousness” in order to attain spiritual truth.

Some of the essays deal with theological ideas and Jewish values, others are about Shabbat and festivals, others reflect on American Jewry and Israel, and some are personal memoirs, including one about his recent pilgrimage to the tombs of Chasidic masters in Ukraine.

But while his thoughts may be radical, he shows a traditional sensibility, stressing the significance of prayer and Torah study.

For him prayer is not supplication to a supernatural person we imagine can intervene in our lives; but a way to open ourselves to greater awareness. “The great gift of mind or awareness that makes us human is a vehicle we can train to see through to the underlying oneness of all that is,” he writes.

In one section, he gives a commentary on one of the more recondite parts of the daily service, the recollection of the daily Temple offerings, which demonstrates his symbolic reading of texts. His love of Hebrew is evident, especially the kind of creative wordplay he learns from the Chasidic masters who used it to draw forth fresh interpretations from the classical sources.

For Shabbat, he offers “ten counsels” on how to observe the day, which include spending quality time with family and friends and study, but switching off electronic devices and TV and avoiding work, travel and spending money.

If his Judaism is inner-directed in one sense, it is outward-facing in another, concerned with the environment and social justice.

His essay on Tishah b’Av bemoans “messianic politics” in Jerusalem and Israeli policy towards the Palestinians.

A sense of Jewish history and memory of the Holocaust will not be enough to keep American Jews Jewish, he argues. “Judaism will be important… because it has something to say about God and the meaning of one’s own life, because it offers a way of being human in a deeply dehumanising age.”

He is surely right in looking to neo-mysticism as an alternative for those who no longer can accept the doctrines of old. Theology is not an ivory-tower pursuit for academicians. It is essential for rabbis who want to offer a spiritual roadmap.

Judaism for the World – Reflections on God, Life and Love is published by Yale University Press, £25