The intensity and violence of persecution against religious minorities around the world is "like nothing we've seen in the past two or three decades" an expert has told Christian Today.

Isaac Six, advocacy director of International Christian Concern (ICC), said: "religious freedom has deteriorated tremendously in certain areas and certain regions of the globe in 2016".

"From our vantage point, conditions in China, India, Russia, Iraq, Syria, Nigeria, and even, to a much lesser degree, in the United States, have been heading in a very negative direction," he added.

"The intensity and violence of persecution taking place today, and the awareness of that violence, is like nothing we've seen in the past two or three decades. Persecution has always existed, but usually those doing the persecuting make some effort to try and hide their actions. Groups like ISIS and Boko Haram have completely defied this convention, brazenly admitting they are targeting Christians and other religious minorities while publishing slick, polished videos of executions and kidnapping victims.

"Suddenly anyone with an internet connection is able to witness persecution taking place in a horrific manner that many Christians probably thought ended 17 centuries ago with the Roman coliseums. Yet while violent Islamic extremism is driving much of the persecution that makes it into the headlines, it is the reaction of other nations in response to this extremism and to persecution that also carries serious implications for religious freedom."

Six accused Russia and China of "routinely" using extremism "as a justification for curtailing religious expression".

Russian President Vladimir Putin in July signed into law the 'Yarovaya' package, under which house churches are illegal and religious activity or evangelism is prohibited anywhere outside a registered church or religious site, including private homes and online. Only named members of religious organisations are now allowed to share their faith, and even informal witnessing between individuals is forbidden. Critics have branded it a draconian attempt to stifle religious freedom under the guise of clamping down on terrorism.

China, meanwhile, appears to be further tightening restrictions placed on the Uighur Muslim community in the Xinjiang region. On Monday, the country's top religious affairs official claimed Islamic extremism had infiltrated inland China from its base on the western border.

But even in the West, "the temptation to ban immigrants on the basis of faith or restrict certain religious dress is sending a signal to the rest of the world that religious freedom is not the universal right we have espoused it to be, but one that really only applies when it's in our perceived best interest," Six said.

"We have to acknowledge that while Christians may be persecuted in more countries around the globe than any other faith, Muslims come in at a close second... Persecution is always wrong, no matter the faith of who is being persecuted."

Six listed Iraq and Syria as countries that remain of particular concern – "given the almost total eradication of Christian communities from those two lands" – but added that the ICC had recorded "a very alarming increase" in violent attacks on Christian communities in India over the past year.

He said threats to religious freedom could be divided into three broad categories.

"The first, and the driving force behind much of the persecution in the world today, is the rise in power and popularity of radical Islamic groups such as Boko Haram and ISIS," he explained. "These extremists have no room whatsoever in their ideology or theology for religious freedom, and they are willing to commit genocide if need be to bring into reality their vision of a pure Islamic world.

"Secondly, autocratic governments are moving backwards in terms of religious freedom. China has cracked down on human rights defenders and religious leaders in the last year on a scale that harkens back to the dark days under Mao Zedong. Russia, with its passage this year of the 'Yarovaya laws' has just curtailed religious freedom for 140 million Russians in a way no one would have predicted at the start of 2016.

"Thirdly," Six added, "cultural acceptance of the importance of religious freedom and religious diversity is waning. In India, nationalist Hindu groups are pushing hard for religious restrictions that would increasingly marginalise minority faiths. In the United States, Christianity and Christians have for decades been lampooned as ignorant, intolerant, and socially backward by the majority of the film and television industry.

"Now Christians who oppose recent shifts in law or popular opinion on topics such as same-sex marriage or abortion are finding themselves the brunt of increasingly vitriolic social hostility or legal action."