Christian growth has stagnated globally while Islam's numbers have almost doubled, according to one researcher.
In a report by Dick Slikker, of the Christian mission consultancy group Project Care, information from the World Christian Database reveals that Christians made up 34.5 per cent of the world's population in 1900, while in 2010 they were 32.9 per cent.
This is contrasted with Islam's growth over the same period, at 12.3 per cent of the population in 1900, rising to 22.5 per cent by 2010. The data shows that the number of Muslims exceeded the number of Roman Catholics in the early 1980s.
Growth and decline in the Christian churches has been divided across various regions, but the general pattern has been that more 'western' industrialised countries have seen their Christian populations decline, while developing countries are seeing increased growth.
The most prominent growth can be seen in Africa where the Christian population increased by 37 per cent between 1900 and 2010. Islam grew only 10 per cent in the same period, making Africa the place where Christians have grown at a faster rate than Muslims.
Within Africa, the fastest growing Christian regions are Eastern Africa, and the Sub Saharan areas of the continent, which both saw 50 per cent Christian population increase between 1900 and 2010.
The most substantial decline for a single continent is in North America, with an 18 per cent drop in Christian affiliation between 1900 and 2010. Europe is in a similar situation with a drop of 16 per cent, while Oceania and Latin America both had declines of 3 per cent.
Focusing on specific regions within continents, the single greatest decline is found in Western Europe, with a drop from 99 per cent Christian in 1900 to 69 per cent in 2010. In the same region Islam's numbers have increased from almost zero per cent in 1900 to 6 per cent in 2010.
Mr Slikker speculates that the decline seen among Christians, especially Protestants, in North America and Western Europe is attributable to "increased materialism, secularism, rationalism, rejection of the notion of spiritual authority outside of oneself".
In the case of Oceania, Mr Slikker notes that while Christianity has declined by 3 per cent between 1900 and 2010, the data also reveals that Christian numbers were rising in that region until 1970.
"It would be of considerable interest to identify the factors behind such developments to learn if any distinct lessons might be apparent," he said.
Asia was the only continent apart from Africa to see Christian growth. The Christian population there grew by 6 per cent between 1900 and 2010. The Islamic population grew by 10 per cent.
Read the report in full here