“Within 48 hours, I received myself about 75 death threats, via text messages and Facebook,” said Imam Ismaeel Chartier, the mosque’s spiritual leader. The declaration in January, and accompanying fear, caused an internal conflict and soon led to the election of a more conservative, older board.

The Shaanti Bhavan Mandir is a surprisingly humble temple to take such a public role in the movement. The small storefront congregation is on Jamaica Avenue in the Richmond Hill neighborhood, under the elevated tracks of the J train. Its small banner is draped over the sign of a former real estate agent’s office whose space the temple is renting. It was founded five years ago by Pandit Manoj Jadubans, 44, a Guyana native, who, with a group of supporters, wanted to broaden what modern Hindu practice could look like.

One of hundreds of small Indo-Caribbean temples in that corner of Queens, it has sought to distinguish itself by focusing on the younger generation, acts of service and the environment. Its youth group’s motto is “the hands that serve are holier than the lips that pray.” Among other actions, it participates in regular beach cleanups though Sadhana, a coalition of progressive Hindus that also played a key role in encouraging the temple to become a sanctuary.

“We are a community largely comprised of immigrants and undocumented immigrants, and we were worried that this step would bring attention to our congregants who are undocumented,” said Ms. Singhroy, 22, a temple and Sadhana member. “But in the end we decided those are the very people we were going to help by taking this step.”

Pandit Manoj announced the temple’s decision on March 19 in front of a packed sanctuary, a glittering array of idols and a photograph of his late guru, Shree Prakash Gossai. “Let the mandirs, the temples, be a place where people can come to feel comforted, protected and feel some sense of worth within their life,” he said.