It is the First Amendment of the Constitution that protects religious freedom, with the Establishment Clause and Free Exercise Clause further safeguarding that right.
A recent report by First Liberty Institute, the Texas-based nonprofit Christian conservative legal organization, shows which U.S. states are making good on that promise — with others falling behind.
The nonprofit compared how the 50 states protect religious liberty through legislation.
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The third annual "Religious Liberty in the States" report ranked the states on an index based on 39 legal provisions that states can adopt to protect religious liberty.
After determining whether states have the statutes, the protections are accumulated into 16 "safeguards," which are averaged to produce one index score per state.
New "safeguards" this year include absentee voting, health-care provisions, health insurance mandates, marriage and wedding issues, religious ceremonial life safeguards, and the Religious Freedom Restoration Act.
"This dynamic index will increasingly represent how well states protect religious liberty in the present and will be less tied to what states did decades ago," said Paul Mueller, associate director of the project, in a press release.
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"Therefore, we expect states to move up (or down) in the annual index ratings based on how actively they choose to protect religious liberty."
Illinois is again considered the No. 1 state for religious liberty in this report, but its score slipped from 85% to 80% due to its failure to adopt new protections to prevent houses of worship from closing, the organization noted.
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Following the Prairie State, Florida, Montana and Arkansas are listed among the top.
Mississippi capped off the top five best states.
"Now is the time for every state to do all they can to protect our first freedom," said Kelly Shackelford, First Liberty Institute's president, CEO and chief counsel, in the release.
"The Religious Liberty in the States index empowers citizens with the knowledge they need to push to ensure their religious liberties are more fully protected."
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Listed at the bottom by First Liberty are California, ranked 48th, and Alaska, at 49th place.
The worst state for religious liberty based on the report is West Virginia at 25%.
First Liberty Institute noted that the state's score rose from the previous year from 14%, due to the adoption of the Religious Freedom Restoration Act.
West Virginia's Gov. Jim Justice, a Republican, signed the law in March prohibiting the state from substantially burdening someone’s constitutional right to freedom of religion unless doing so "is essential to further a compelling governmental interest," the Associated Press reported at the time.
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First Liberty noted on its website, "Many states are making big improvements, and the data clearly shows it. But there’s still plenty of room for progress."
It added, "The majority of states are doing less than half of what they could be doing. Only 12 states had 50% or higher of the religious liberty protections. As [stated in] the report, most states on average adopt less than half of the safeguards that protect religious liberty."
Fox News Digital reached out to First Liberty Institute for additional comment.