The figure above comes from a 2012 Pew Research Center demographic study. It concluded there were 1.6 billion Muslims living in the world, which would be over 1.7 billion today with the current population of 7.4 billion people worldwide and the same percentage of Muslims globally.
Much of Pew's research relies on percentages, which can be somewhat misleading. If Pew concludes "little support" for certain beliefs because only 10 percent of a population agrees with their survey question, that is potentially 170 million people in the Muslim world. So what are the predominant beliefs?
To start, an overwhelming number believe religion is very important in their lives.
In addition, in "32 of the 39 countries surveyed, half or more Muslims say there is only one correct way to understand the teachings of Islam".
The majority of Muslims in Sub-Saharan Africa also believe the Quran should be read literally. The survey did not ask this question in other areas of the world.
The information above can be synthesized as stating that over 800 million Muslims take their religion very seriously and believe that there is only one correct understanding of it, a literal one.
Next, we can ask what all this serious, correct, and literal understanding means to most Muslims. First, many believe that Sharia should be the official law of the land. "Overwhelming percentages of Muslims in many countries want Islamic law (sharia) to be the official law of the land, according to a worldwide survey by the Pew Research Center. But many supporters of sharia say it should apply only to their country’s Muslim population."
What does, "many supporters of sharia say it should apply only to their country’s Muslim population," mean? Somewhere between 51 to 64 percent of the overwhelming majority of Muslims that believe Sharia should be the official law of the land believe it should only apply to Muslims. That leaves 36 to 49 percent of that overwhelming majority that believe otherwise. That still leaves over 100 million Muslims in the world that potentially believe Sharia should be the law of the land and not necessarily only for Muslims.
The entire report titled "The World’s Muslims: Religion, Politics and Society" is interesting and worth looking over, just keep in mind the absolute numbers when looking at small percentages. One percent of 1.7 billion Muslims is still 17 million people. It is these absolute numbers that worry people, not the relative percentages often thrown around that hide the fact, for example, that millions of Muslims around the world believe that suicide bombing is justified.
While 72 percent of global Muslims believe suicide bombing is never justified in defense of Islam, "3% of Muslims worldwide say suicide bombings and other violence against civilian targets are often justified, while 7% of U.S. Muslims and a global median of 8% of Muslims say such attacks are sometimes justified to defend Islam". That is 51 million people that believe violence is often justified and 136 million people that believe violence is sometimes justified to defend Islam.