Pew Research Center in America also said by the end of the century there will be around 1 per cent more Muslims in the world than Christians.
It says reasons for the changes in demographics include migration from predominantly Islamic countries in Asia and the South Pacific to more Christian, western regions.
For example the Center predicts a marked change in America, one of the world's most Christian countries demographically. It predicts the proportion of Muslims will double there by 2050, from around 1 per cent (3.3 million people approximately) of the population today to approximately 2.1 per cent.
It also cites a difference in birth rates as a factor in the world demographic changes, saying that Muslim families have 3.1 children on average compared to 2.3 for every other religious group combined on average.
Currently around 2.2 billion - or 31 per cent - of people in the world are Christians. This compares to around 1.6 billion, or 23 per cent, who are Muslims.
