"USCIRF added a special emphasis on non-state actors, as their violent actions are a growing threat to religious freedom," said Knox Thames, the commission's director of policy and research.
"Violence perpetrated by non-state actors against religious minorities and others who conflict with their worldview is increasingly common, with incidents occurring in places as diverse as Pakistan and Nigeria."
Somalia, for example, which doesn't make the list, is home to al-Shabaab, a U.S.-designated foreign terrorist organization that has brutally suppressed Christians and Sufi Muslims who do not subscribe to its radical interpretation of Islam.
"Somalis accused of committing crimes or who al-Shabaab deems to have deviated from accepted behaviors are punished through stoning, amputation, flogging, and/or detention," according to the report.
On its 15-nation list of the worse offenders, USCIRF includes eight that the U.S. State Department also considers "Countries of Particular Concern": Burma, China, Eritrea, Iran, North Korea, Saudi Arabia, Sudan and Uzbekistan.
But, as in years past, the commission wants the State Department to add seven more: Egypt, Iraq, Nigeria, Pakistan, Tajikistan, Turkmenistan and Vietnam.
This year's USCIRF list is one country smaller than it was in 2012. Gone is Turkey, whose addition caused an uproar among Turks who called the designation unfounded and damaging to USCIRF's reputation.
Orthodox Christians welcomed the 2012 designation after years of arguing that Turkey home to Ecumenical Patriarch Bartholomew, spiritual leader of the world's 250 million Orthodox Christians continues to shutter their seminary in that country and withholds legal status from many religious groups.
Thames said the commission's decision against designating Turkey as a "country of particular concern" this year was unanimous.
The nation can point to a genuine loosening of restrictions on religious communities, but "nevertheless," the report concludes, "the Turkish government's interpretation of secularism requires absolute state control over all aspects of religion in the public sphere."
But the decision to "promote" Turkey to a country "to be monitored" struck several commissioners as too lenient.
Last year, it was "an error to place Turkey among the world's worst violators of religious freedom," four of eight commissioners wrote in a dissent included in this year's report. "But this year's designation has erred in the opposite direction."
The dissenters want it to be designated a "Tier 2" country, just below the most concerning 15.