Skip to Main Content

Apply Now to the University of Wyoming apply now

UW Religion Today Column for March 13-19: Is Christianity Successful?

March 8, 2011

"Religion Today" is contributed by the University of Wyoming's Religious Studies Program to examine and promote discussion of religious issues.

By Paul V.M. Flesher

The question of whether or not Christianity is successful depends on how success is measured. Why not treat the question as a horse race and ask "what is the biggest religion?"

By this approach, Christianity is way out in front. General consensus among the bean counters is that Christianity has approximately 2.1 billion members while the next largest world religion, Islam, comes in at just 1.5 billion. At 900 million, Hinduism forms the third largest religion. Estimating the number of adherents on a world scale is quite difficult, but these are fairly reliable numbers, give or take a couple hundred million.

At about a third of the world's population, Christianity constitutes the world's largest religion. That means it is the most successful, right? 

Well, it depends on the definition of Christian. To arrive at 2.1 billion, the experts included every person or group of people who self-identify as Christian. They did not make judgments beyond that about who is or who is not a Christian. So if you believe that some people who call themselves Christians are not, that they do not count (pun intended), then the number of Christians in the world will be significantly smaller.

Christianity has a history of not being inclusive. In the first few centuries, Christians created a variety of beliefs about the nature of God and Jesus. When Christianity began its official organization under Emperor Constantine and his successors in the fourth century, it began by formalizing doctrine, that is, beliefs to which members had to assent, and then declaring other beliefs to be heresies.

For example, the Council of Chalcedon in the fifth century agreed that God was Three-in-One: the Trinity of the Father, Son, and Holy Spirit. Those who did not agree were deemed heretics and excluded from the Christian Church. This led to the formation of churches such as the Armenian Orthodox, Syrian Orthodox and Coptic Orthodox churches. These churches continue today and are included in the population count just mentioned.

Conversely, Protestant Christianity began as a rejection of Catholicism and many Protestants today still do not consider Catholics to be Christians. By this standard, then, Christianity is actually smaller than Catholicism, for if the 1.1 billion Catholics are not counted, then there are only one billion Christians left. That is also significantly fewer members than Islam, which would suggest that Christianity is not so successful.

Of the one billion non-Catholic Christians, only 600 to 700 million are Protestants. Out of these, 75 million belong to the Anglican Church, the largest organized Protestant denomination. Liberal Protestants make up about 150 million, while conservative Protestants are approximately 200 million, along with about 105 million Pentecostalists. If these last two groups make up the classification known as Evangelical Protestants, then there are just slightly more that 300 million of them, which is about 15 percent of the 2.1 billion Christians worldwide.

The following branches of Christianity make up the bulk of the remaining 300 to 400 million Christians: 110 million members of indigenous Christian churches in Africa, 90 million Russian Orthodox, 20 million Greek Orthodox, 12 million Mormons, about a million and a half members of "New Thought" churches such as Unitarianism and Christian Science, and roughly 300,000 Quakers. While Greek and Russian Orthodox adhere to Christianity's most traditional beliefs, other groups such as Quakers, Mormons and the African churches have reformulated those beliefs in various ways.

The point is this: Christianity can be considered a success at bringing souls to Christ only if an extremely broad definition of Christianity is used. Otherwise, the best that can be said is that only a bit more than half of those considered Christians by this count (i.e., Catholics) have gained salvation. The debate over who is really a Christian has a key impact on the success of God's plan for the salvation of humanity is understood. The narrower the definition of "Christian," the less successful God's plan has been.

Note: The population figures in today's column come from

Flesher is director of UW's Religious Studies Program. Past columns and more information about the program can be found on the Web at To comment on this column, visit

1000 E. University Ave. Laramie, WY 82071
UW Operators (307) 766-1121 | Contact Us | Download Adobe Reader

Accreditation | Virtual Tour | Emergency Preparedness | Employment at UW | Privacy Policy | Harassment & Discrimination | Accessibility Accessibility information icon