Messianism is the world’s most powerful idea, humanity’s most compelling vision. Not only is it the underpinning of the world’s most populous religion, Christianity, it is also the engine for human progress itself. Only through a belief that history is not cyclical but linear, that positive steps in human advancement are cumulative rather than short-lived, that as a race we can step together out of the shadows and into the light, can there hope for collective human progress.

It is therefore fascinating to witness – once a year – the tremendous energy unleashed by the Chabad messianic movement as it congregates and detonates at world Chabad headquarters in Brooklyn.

The Jewish festival of Sukkot brings together two very different strands of the global Chabad movement. On the one hand, there is mainstream Chabad comprised of residents of Crown Heights – the global hub – together with the worldwide network of Chabad emissaries. Their strength is their professionalism, dedication, and impact.

On the other hand there are the Chabad messianists, a minority to be sure, but vocal, visible, determined, and brimming with life.

Mainstream Chabad is uncomfortable with the messianists, believing they give both the movement and the Rebbe himself a bad name. The messianists are millennial, apocalyptic, and, to many minds, irrational. They want to push both Chabad and Judaism into the end of days.

But there can be no denying that they have tapped into an energy source that appears near infinite.

When I was a young Chabad student in Crown Heights what I remember most was the limitless energy we all experienced in the Rebbe’s court. On Sukkot we could dance nine days running without tiring. We could go for a week with barely any sleep. The Rebbe – then in his eighties – set the pace with superhuman strength and inexplicable vigor.

That was more than twenty years ago.

Since then, Chabad has conquered the world and gone mainstream, sprouting educational centers in every point of the globe. My wife and I recently spent Shabbat with Chabad of Korea right after I spoke at Seoul’s Olympic Stadium at a global peace summit. A few weeks earlier I had spoken at Chabad of Aspen, Colorado. The local Chabad centers in these two very different places had in common the outstanding young Chabad rabbis, true soldiers of the Jewish people. Watching their impact on their respective communities was inspiring.

But for all that, Chabad today – as a movement that has now gone mainstream – has learned to eschew controversy. Gone are the days when Chabad agitated for the territorial integrity of the State of Israel and public stands against trading land for a fraudulent peace. Gone too are the Chabad emphasis on messianism as being central to Judaism and the Jewish future. Chabad today is effective if not conventional, essential if not somewhat predictable. Its focus: opening nurseries and day schools, synagogues and mikvehs, looking after special needs children (Friendship Circle) and the elderly, running Sunday schools and day camps. And to quote Carly Simon, nobody does it better.

It is to this side of Chabad that I adhere and this vision for the building of Jewish life that I am dedicated. Chabad justly evokes in every Jew on earth a feeling of both awe and gratitude.

Without Chabad the Jewish world would be up a creek without a paddle.

But even as someone who prides himself on his rationality, I cannot help but be somewhat jealous of the go-for-broke mentality of the other side of the movement, the messianists. The belief that humankind can attain an age of perfection, a belief that Judaism has a global, universal vision that is not limited to Jews, a dismissal of money and materialism in favor of a purely spiritual calling, and placing faith in a great leader who prompts us to embrace that era.

To be sure, I follow the ruling of Maimonides that the Messiah must be a living man who fulfills the Messianic prophecies which rules out anyone – however great – that has passed from this world without ushering in an age of universal peace, rebuilt the Temple, and gathered in all Jewish exiles. That would exclude my Rebbe as it would exclude all the other great leaders of the Jewish people through the ages however much they have devoted their lives to our people.

But that does not change my clear memory of the Rebbe’s incessant and unyielding public calls for Jews to work toward a messianic future, to dedicate every positive deed toward his coming, and to never fear controversy in the pursuit of every aspect of Jewish belief.