When people try to figure out the secret to Chabad’s phenomenal success, they usually mention the movement’s unconditional love toward their fellow Jews. I can see why. Go to any of the thousands of Chabad centers around the world and you’ll be welcomed with open arms. A Chabad emissary sees holiness in every Jew—it’s as simple and powerful as that.

But when I had dinner the other night with close to 5,000 Chabad emissaries from around the globe at their annual convention in Brooklyn, I discovered another key to their success— something less obvious.

It came to me during one of several speeches during the night. A senior emissary from England was telling the story of a woman who had just lost her husband, and who was adamant that she wanted a non-religious ceremony with the body cremated. Of course, the rabbi tried to gently convince her to do a proper Jewish burial, but the woman wouldn’t budge. So, they negotiated. The rabbi was flexible on things that were not absolutely mandated by Jewish law, but he couldn’t compromise on cremation, which is a serious no-no in traditional Judaism.

As he recounted the story in minute detail, I looked around at the faces of the emissaries around me. I could see a yearning in their eyes. I could feel this collective sentiment throughout the giant hall—thousands of men in beards and black hats, listening attentively to every word, yearning for a happy ending.

When the rabbi got to the end of his story, with the woman finally relenting and saying, “OK, rabbi, fill out that green burial form before I change my mind,” it was as if he had announced a $100 million gift to Chabad. The place exploded with joy. There was a thrill of victory in the air. What was that victory? A Jewish man would be buried according to Jewish law.

That anecdote tells you much of what you need to know about arguably the most successful movement in Jewish history— a movement obsessed with observing God’s commandments.

What is so extraordinary about this obsession is that it flies in the face of modern-day wisdom about how to attract people to the Jewish tradition: “Don’t obsess with all the rules and commandments! You’ll just turn people off.”

Clearly, Chabad didn’t get the memo. Every Chabadnik I’ve ever met has been obsessed with the commandments, or, as they like call them, the mitzvot: Did you put on tefilin this morning? Did you make a bracha in the succah? Do you need lulav and etrog? Did you listen to the megilla? Did you light the Chanukkah candles? Do you have shmurra matzah for your seder? Do you need Shabbat candles? Do you have mezuzzas in your office? Can you come to a Torah class tomorrow? What are you doing Friday night?

Every day and every minute in over 70 countries, Chabad emissaries ask those very questions. They don’t discuss five-year plans or try to sell you on memberships. Instead of a long-term commitment, they ask you to do a mitzvah. It may be a little uncomfortable for someone who’s not into it, but there’s something disarming and innocent about asking someone to do a good deed.

This is the great enigma of the Chabad movement—how an ultra-Orthodox sect obsessed with observing the commandments became so mainstream and popular. It’s too easy to explain it by saying, “Oh, they’re so warm and loving that it breaks down all barriers.”

That is certainly true—their warmth and love moves people. But what drives the movement itself is a deep, mystical attachment to the mitzvah. Take away the mitzvah and the “love of our fellow Jews” becomes an abstract and passive idea. The mitzvah is what turns their love into a verb. It’s what makes them express this love in the deepest possible way, by sharing something they cherish—the holy act of following God’s commandments.

This transcendent attachment to the mitzvah is what binds the movement and keeps the emissaries charging ahead. They have complete faith in the power of the mitzvah to change the world. If a focus group tells them not to bother people in public, they ignore it.  They don’t agonize over the Pew study. They don’t wallow in creative tension or theological ambiguities. They have one global model, and it has no ambiguity. It’s called “We want you to do a mitzvah. The world needs it.”

How do you beat that for clarity of purpose?

Their faith in God, in Torah, in their fellow Jews and in humanity are all wrapped up in their faith in the mitzvah. They’re not live and let live— they’re do and help do. That is the essential lesson they learned from their beloved Rebbe: Helping a Jew do a mitzvah is the best way to say, “I love you.”