Jenkins notes that while Islam has increased faster than Christianity in proportion to the total population of the earth (growing from about 12% of the population to approximately 22% today) while Christianity has maintained its 33% status, the real difference comes in the way that new adherents were added.2 Islam has expanded in its traditional countries simply through rising fertility rates. Christianity continues to expand in historically non-Christian countries, such as those on the African continent, where missionaries have been doing the work of spreading the Christian message.
Let me be clear that the truth value of any belief system is not determined by how many people believe in it. Simply holding to the majority position proves nothing. It is easy, though, to show that Christianity is not growing either by compulsion or by fertility. The Christian strongholds of Europe and other western countries are in a famously rapid population decline. In the last century, Europe went from comprising 66% of the world's Christians to making up only 25% today.3 The African continent has seen a boom, though. According to Jenkins, Christianity has exploded an astounding 4,930%.4
The Effects of Evangelization: Stable DemocraciesWhy does this matter? It turns out, it matters quite a bit. A very meticulous study by Robert Woodberry shows convincingly that those Christian missionaries that sought to evangelize Africa had an incredibly positive effect for the nations where they flourished.5 Woodberry's data clearly shows that nations who had conversionary Protestant missionaries do their work set those nations on a road to literacy and stable democracy.
A recent article in Christianity Today highlights some of the advantages:
"Areas where Protestant missionaries had a significant presence in the past are on average more economically developed today, with comparatively better health, lower infant mortality, lower corruption, greater literacy, higher educational attainment (especially for women), and more robust membership in nongovernmental associations.The Christian worldview has proven itself time and again as the single best way to ease suffering and raise the standard of living for its adherents. This as it continues to spread even today through the same means it did for the past 19 centuries. No violence necessary.
In short: Want a blossoming democracy today? The solution is simple—if you have a time machine: Send a 19th-century missionary."6
So, to claim that Christianity spread through violence is demonstrably false. As to the claim about the truth value of Christianity, I've provided many arguments as to why Christianity is a faith based on evidence. No one threatened me to believe or else! I am convinced by the truth of Christianity's arguments and I'm not alone. I know of many atheists who looked at the evidence and converted to Christianity because of its truth value. And we have the real world effects of Christian missionaries spreading the Christian worldview to countries where the measurable effects are the betterment of lives.
2. "The Numbers." FastestGrowingReligion.com. http://fastestgrowingreligion.com/numbers.html Accessed 6/9/2014.
3. "Global Christianity – A Report on the Size and Distribution of the World's Christian Population." Pew Center of Religion and Public Life. 12/19/2011. http://www.pewforum.org/2011/12/19/global-christianity-exec/ Accessed 6/9/2014.
4. Jenkins, Ibid.
5. Andrea Palpant Dilley. "The Surprising Discovery About Those Colonialist, Proselytizing Missionaries." Christianity Today. 1/8/2014. https://www.disciplenations.org/media/CT-Article-On-Missionaries-And-Global-Democracy.pdf Accessed 6/9/2014.
6. Dilley, Ibid.