Although all of them have their historical roots in Christian theology and tradition, and although most would identify themselves as Christian, many would not identify others within the larger category as Christian. Most Baptists and fundamentalists (Christian Fundamentalism), for example, would not acknowledge Mormonism or Christian Science as Christian. In fact, the nearly 77 percent of Americans who self-identify as Christian are a diverse pluribus of Christianities that are far from any collective unity.
As of the early 21st century, Christianity has approximately 2.4 billion adherents. The faith represents about a third of the world's population and is the largest religion in the world. Christians have composed about 33 percent of the world's population for around 100 years. The largest Christian denomination is the Roman Catholic Church, with 1.17 billion adherents, representing half of all Christians.
According to a 2011 Pew Research Center survey, there were 2.2 billion Christians around the world in 2010, up from about 600 million in 1910. By 2050, the Christian population is expected to exceed 3 billion. According to a 2012 Pew Research Center survey Christianity will remain the world's largest religion in 2050, if current trends continue.
Christianity remains the dominant religion in the Western World, where 70% are Christians. According to 2012 Pew Research Center survey if current trends continue, Christianity will remains the world's largest religion by year 2050. By 2050, the Christian population is expected to exceed 3 billion. While Muslims have an average of 3.1 children per woman—the highest rate of all religious groups. Christians are second, with 2.7 children per woman. High birth rates and conversion were cited as the reason for the Christian population growths. A 2015 study found that approximately 10.2 million Muslim converted to Christianity. Christianity is growing in Africa, Asia, Latin America, Muslim world, and Oceania.
In Arabic-speaking cultures, two words are commonly used for Christians: Naṣrānī (نصراني), plural Naṣārā (نصارى) is generally understood to be derived from Nazareth through the Syriac (Aramaic); Masīḥī (مسيحي) means followers of the Messiah. The term Nasara rose to prominence in July 2014, after the Fall of Mosul to the terrorist organization Islamic State of Iraq and the Levant. The nun or ن— the first letter of Nasara—was spray-painted on the property of Christians ejected from the city.
According to a study from 2015, Christians hold the largest amount of wealth (55% of the total world wealth), followed by Muslims (5.8%), Hindus (3.3%) and Jews (1.1%). According to the same study it was found that adherents under the classification Irreligion or other religions hold about 34.8% of the total global wealth. A study done by the nonpartisan wealth research firm New World Wealth found that 56.2% of the 13.1 million millionaires in the world were Christians.
A Pew Center study about religion and education around the world in 2016, found that Christians ranked as the second most educated religious group around in the world after Jews with an average of 9.3 years of schooling, and the highest of years of schooling among Christians found in Germany (13.6), New Zealand (13.5) and Estonia (13.1). Christians were also found to have the second highest number of graduate and post-graduate degrees per capita while in absolute numbers ranked in the first place (220 million). Between the various Christian communities, Singapore outranks other nations in terms of Christians who obtain a university degree in institutions of higher education (67%), followed by the Christians of Israel (63%), and the Christians of Georgia (57%).