The Prince of Wales has urged faith leaders to ensure that people within their own tradition respected those of others.
His plea came in a video message recorded for the launch of a report on religious freedom, compiled by the international charity Aid to the Church in Need.
He said the "horrendous and heartbreaking" events in Iraq and Syria had brought the subject of religious freedom and persecution to the forefront of the world's news.
"We have learnt with mounting despair of the expulsion of Christians, Muslims and Yazidis from towns and cities that their ancestors have occupied for centuries," he said.
"Sadly, incidents of violence in Iraq and Syria are not isolated. They are found throughout some, though not all, of the Middle East; in some African nations; and in many countries across Asia.
"Thankfully, despite this bleak picture, there are inspirational people of different faiths joining together to overcome division and hatred. And, if I might say so, it is a well-established principle of inter-faith dialogue that we judge each other by the best expression of our faith rather than the worst."
The Prince said that over several decades he had been working to encourage dialogue and greater understanding between different faith traditions.
He said: "It is an indescribable tragedy that Christianity is now under such threat in the Middle East - an area where Christians have lived for 2,000 years, and across which Islam spread in 700 AD, with people of different faiths living together peaceably for centuries.
"It seems to me that our future as a free society - both here in Britain and throughout the world - depends on recognising the crucial role played by people of faith. And, of course, religious faith is all the more convincing to those outside the faith when it is expressed with humility and compassion, giving space to others, whatever their beliefs."
He suggested ways to bring about an improvement. "First and foremost, rather than remaining silent, faith leaders have, it seems to me, a responsibility to ensure that people within their own tradition respect people from other faith traditions. We have yet to see the full potential of faith communities working together."
Secondly, it was essential that governments honoured their duty to uphold the right of people to practise their faith, he said.
"Article 18 of the Universal Declaration of Human Rights is clear in stating that this right includes the freedom to change one's religion or belief. Yet even in the West this right is often challenged. Sadly, in many other countries, an absence of freedom to determine one's own faith is woven into the laws and customs of the nation."
The report by the Catholic charity, studying the period October 2012 to June 2014, finds that of the 196 countries in the world, 81 - or 41% - are identified as places where religious freedom is impaired or in decline.
Some 20 countries are designated as "high" with regard to lack of religious freedom. Of these, 14 experience religious persecution linked to extremist Islam. These are: Afghanistan, Central African Republic, Egypt, Iran, Iraq, Libya, Maldives, Nigeria, Pakistan, Saudi Arabia, Somalia, Sudan, Syria and Yemen.
In the remaining six countries, religious persecution is linked to authoritarian regimes. These are: Burma (Myanmar), China, Eritrea, North Korea, Azerbaijan and Uzbekistan.
In the period under review, global religious freedom entered a period of "serious decline", the report says.
"The impression given by global media headlines of a rising tide of persecution aimed at marginalised religious communities is supported by this research," it adds.
Muslim countries predominate in the list of states with the most serious religious freedom violations.
Religious freedom is in decline in Western countries that are predominantly or historically Christian, with one reason being that openness to religious freedom is under threat from increasing concern about extremism, the report found.
Christians remain the most persecuted religious minority, due partly to their wide geographic spread and high relative numbers, the report says.
Muslims are also experiencing a serious degree of persecution and discrimination, both at the hands of other Muslims and from authoritarian governments, it said.
Jews in Western Europe are subject to violence and other abuse that is generally low-level, the report found. However, such problems have grown, prompting increased emigration to Israel.
Some positive signs of religious co-operation were identified, but these were often the result of local initiatives rather than progress at a national level.
The report's authors say: "We conclude that, to reverse the disturbing trends identified in this report, responsibility for combating violence and persecution rests, first and foremost, within religious communities themselves.
"The necessity for all religious leaders to loudly proclaim their opposition to religiously inspired violence, and to reaffirm their support for religious tolerance, is becoming ever more urgent."