A new, comprehensive study of over 200 countries finds that there are 1.57 billion Muslims of all ages living in the world today - 23% of an estimated 2009 world population of 6.8 billion.

The biggest gains due to change in religious affiliation in the US have been among those who say they are not affiliated with any particular faith, according to a new study.

Despite having a different faith tradition to the Christian majority in the United States, Muslim Americans share much in common with other US religious groups, including white evangelical Protestants, a new study has found.