Every religion has its true believers and its doubters, its pious and its pragmatists, but new evidence suggests that Muslims tend to be more committed to their faith than other believers.
Muslims are much more likely than Christians and Hindus to say that their own faith is the only true path to paradise, according to a recent global survey, and they are more inclined to say their religion is an important part of their daily lives.
Muslims also have a much greater tendency to say their religion motivates them to do good works, said the survey, released over the summer by Ipsos-Mori, a British research company that polls around the world.
Islam is the world's second-largest religion - behind Christianity and ahead of Hinduism, the third largest. With some 1.5 billion followers and rising, Islam's influence may be growing even faster than its numbers as the Arab Spring topples long-reigning secular rulers and opens the way to religiously inspired political parties.
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But while there's no doubt about the importance of Islam, experts have different theories about why Muslims appear to be more religious than members of other global faiths - and contrasting views on whether to fear the depth of Muslims' commitment to their faith.
One explanation lies in current affairs, says Azyumardi Azra, an expert on Islam in Indonesia, the world's most populous Muslim majority country.
Many Muslims increasingly define themselves in contrast with what they see as the Christian West, says Azra, the director of the graduate school at the State Islamic University in Jakarta.
"When they confront the West that they perceive or misperceive as morally in decline, many Muslims feel that Islam is the best way of life. Islam for them is the only salvation," he says.
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That feeling has become stronger since the September 11 attacks, as many Muslims believe there is a "growing conflict between Islam and the so-called West," he says.
"Unfortunately this growing attachment to Islam among Muslims in general has been used and abused by literal-minded Muslims and the jihadists for their own purposes," he says.
But other experts say that deep religious commitment doesn't necessarily lead to violence.
"Being more religious doesn't necessarily mean that they will become suicide bombers," says Ed Husain, a former radical Islamist who is now a Middle East expert at the Council on Foreign Relations in New York.
In fact, Husain argues that religious upbringing "could be an antidote" to radicalism.
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The people most likely to become Islamist radicals, he says, are those who were raised without a religious education and came to Islam later, as "born-agains."
Muslims raised with a grounding in their religion are better able to resist the distortions of Islam peddled by recruiters to radical causes, some experts like Husain argue, making them less likely to turn to violence.
But he agrees that Muslims are strongly attached to their faith, and says the reason lies in the religion itself.
"Muslims have this mindset that we alone possess the final truth," Husain says.
Muslims believe "Jews and Christians went before us and Mohammed was the last prophet," says Husain, whose book "The Islamist" chronicles his experiences with radicals. "Our prophet aimed to nullify the message of the previous prophets."
The depth of the Muslim commitment to Islam is not only a matter of theology and current events, but of education and history, as well, other experts say.
"Where religion is linked into the state institutions, where religion is deeply ingrained from childhood, you are getting this feeling that 'My way is the only way,'" says Fiyaz Mughal, the director of Faith Matters, a conflict-resolution organization in London.
The Ipsos-Mori survey results included two countries with a strong link between religion and the state: Legally Muslim Saudi Arabia, which calls itself the guardian of Islam's two holiest sites, Mecca and Medina; and Indonesia, home of the world's largest Muslim population.
The third majority Muslim country in the study is Turkey, which has a very different relationship with religion. It was founded after World War I as a legally secular country. But despite generations of trying to separate mosque and state, Turkey is now governed by an Islam-inspired party, the AKP.
Turkey's experience shows how difficult it can be to untangle government and religion in Muslim majority countries and helps explain the Muslim commitment to their religion, says Azyumardi Azra, the Indonesia expert.
He notes that there has been no "Enlightenment" in Islam as there was in Europe in the 17th and 18th centuries, weakening the link between church and state in many Christian countries.
"Muslim communities have never experienced intense secularization that took place in Europe and the West in general," says Azra. "So Islam is still adhered to very strongly."
But it's not only the link between mosque and state in many Muslim majority countries that ties followers to their faith, says professor Akbar Ahmed, a former Pakistani diplomat who has written a book about Islam around the world.
Like Christians who wear "What Would Jesus Do?" bracelets, many Muslims feel a deep personal connection to the founder of their faith, the prophet Muhammad, he says.
Muhammad isn't simply a historical figure to them, but rather a personal inspiration to hundreds of millions of people around the world today.
"When a Muslim is fasting or is asked to give charity or behave in a certain way, he is constantly reminded of the example set by the prophet many centuries ago," argues Ahmed, the author of "Journey Into Islam: The Crisis of Globalization."
His book is based on interviews with Muslims around the world, and one thing he found wherever he traveled was admiration for Muhammad.
"One of the questions was, 'Who is your role model?' From Morocco to Indonesia, it was the prophet, the prophet, the prophet," says Ahmed, the Ibn Khaldun Chair of Islamic Studies at American University in Washington.
But while Ahmed sees similar patterns across the Islamic world, Ed Husain, the former radical, said it was important to understand its diversity, as well.
"There is no monolithic religiosity - Muslims in Indonesia and Saudi Arabia are following different versions of Islam," says Husain. "All we're seeing (in the survey) is an adherence to a faith."
Political scientist Farid Senzai, director of research at the Institute for Social Policy and Understanding in Washington, raised questions about the survey's findings.
"Look at the countries that are surveyed - Saudi Arabia, Indonesia and Turkey," he says. "There are about 300 million Muslims in those three countries, (who make up) about 20% of Muslims globally."
Islam is "incredibly important" in Saudi Arabia, he says.
"But in Tunisia or Morocco you could have had a different result. It would have been nice if they had picked a few more Arab countries and had a bit more diversity," says Senzai.
The pollster, Ipsos-Mori, does monthly surveys in 24 countries, three of which are majority Muslim – Turkey, Indonesia and Saudi Arabia. The other countries range from India to the United States, and Mexico to South Korea, and are the same each month, regardless of the subject the pollsters are investigating.
In the survey released in July, about six in 10 Muslims in the survey said their religion was the only way to salvation, while only a quarter of Hindus and two out of 10 Christians made that claim about their own faiths.
More than nine out of 10 Muslims said their faith was important in their lives, while the figure was 86% for Hindus and 66% for Christians.
Ipsos-Mori surveyed 18,473 adults via an online panel in April and released the findings in July. Results were weighted to make the results as representative as possible, but the pollster cautioned that because the survey was conducted online, it was harder to get representative results in poorer countries where internet access is not widespread.
CNN polling director Keating Holland also warns that in an "opt-in" survey, where respondents actively choose to participate, results tend to come from "people who are confident in their opinions and express them openly... not good for intensely private matters like faith or income or sex."
Online surveys in countries that are not entirely free are also open to the possibility that pollsters get "the approved response" in those nations, "where the people who are most likely to be willing to talk about such matters are the ones who hold, or at least verbalize, opinions that won't get them in trouble if they are expressed," Holland says.
That may have been an issue in Saudi Arabia, where respondents were given the choice of not answering questions on religion due to their potential sensitivity in the kingdom. The Saudi sample was the smallest, with 354 participants, meaning "findings for Saudi Arabia must be treated with caution," Ipsos-Mori said.
About 1,000 people participated in most countries, but sample sizes were smaller in the three majority Muslim countries and in eight other countries.
The survey participants did not reflect the true percentage of Christians and Muslims in the world. Christians were over-represented – as were people who said they had no religion – and Muslims were under-represented.
Nearly half the respondents identified themselves as Christian. Eleven percent were Muslim, 4% were Buddhist, 3% were Hindu and 3% were "other." A quarter said they had no religion and 6% refused to say.
Fiyaz Mughal, the interfaith expert, argues that even though the countries surveyed might not be representative of the entire Muslim world, the findings about Muslims rang broadly true. Muslims in different countries were committed to their faith for different reasons, he says.
"Saudi Arabia is an institutionally religious state. Indonesia has religion tied into its culture," says Mughal.
But Muslim immigrants to Europe also show strong ties to their religion, either as a defense mechanism in the face of a perceived threat, or because of an effort to cling to identity, he contends.
He detects a link between insular communities and commitment to faith regardless of what religion is involved. It is prevalent in Muslim Saudi Arabia, but he has seen it among Israeli Jews as well, he says.
"The Israeli Jewish perspective is that (the dispute with the Palestinians) is a conflict of land and religion which are integrally linked," Mughal says.
"What does play a role in that scenario is a sense of isolationism and seclusion in Israeli Jewish religious communities, a growing trend to say, 'Our way is the only way,'" he says.
Religious leaders of all faiths need to combat those kinds of attitudes because of the greater diversity people encounter in the world today, he argues.
They have a responsibility to teach their congregations "that if they are following a religion, it is not as brutal or exclusive as possible," Mughal says. "Things are changing. The world is a different place from what it was even 20 years ago."
Politicians, too, "need to take these issues quite seriously," he says.
"In the Middle East there are countries - the Saudi Arabias - where you need to be saying that diversity, while it may not be a part of the country, is something they have to deal with when moving in a globalized area," he says.
But Senzai, the political scientist, says that it's also important for the West to take the Muslim world on its own terms.
"Many Muslims want religion to play a role in politics," he says. "To assume that everyone around the world wants to be like the West - that they want liberal secular democracy - is an absurd idea."
