Updated at 5:20 p.m. ET

In what is believed to be a first in the United States, the Common Council of Madison, Wis., has voted to amend the city's equal opportunities ordinance "to add nonreligion as a protected class."

The legislation adds atheists to the categories of people who could potentially face discrimination. It was co-sponsored by 14 of the council's 20 members and approved without objection Tuesday night.

Atheism is defined in the ordinance as "the disbelief or lack of belief in the existence of God or gods."

"This is important because I believe it is only fair that if we protect religion, in all its varieties, we should also protect non-religion from discrimination. It's only fair," said Alderwoman Anita Weier, the bill's chief sponsor, according to Madison's WISC TV. The addition of atheism to the ranks of protected classes comes at a time when "religious freedom" laws are in the spotlight — particularly in Indiana, where a controversial new law is seen as allowing businesses to refuse service to people based on their sexual orientation or gender identity.

Madison's amendment will take effect when it's officially published, a step that follows the mayor's signing of the council's proceedings.

Several representatives from the Freedom From Religion Foundation, which is based in Madison, spoke in favor of the bill at Tuesday night's council meeting.

"We encourage freethought activists — including the increasing number of local public officials who are atheists or agnostics — to work to introduce and replicate this protection at their city, county or even state levels," says Annie Laurie Gaylor, FFRF's co-president.

The new legislation inserts the words "or nonreligion" after "religion" in several sections of the city of Madison's legal code.

For example, here's how the city lists its protected class:

"Protected class membership means a group of natural persons, or a natural person, who may be categorized because of their ability to satisfy the definition of one or more of the following groups or classes: sex, race, religion or nonreligion, color, national origin or ancestry, citizenship status, age, handicap/disability, marital status, source of income, arrest record or conviction record, less than honorable discharge, physical appearance, sexual orientation, gender identity, genetic identity, political beliefs, familial status, student, domestic partner, or receipt of rental assistance." Copyright 2019 NPR. To see more, visit https://www.npr.org.