protestantism is the second largest major group of christians by number of followers. estimates vary from 800 million to a billion, or nearly 40% of all christians. the main reason for this wide range is the lack of a common agreement among scholars as to which denominations constitute protestantism. for instance, most sources but not all include anabaptism, anglicanism, baptists and independent nondenominational christianity as part of protestantism. moreover, protestant denominations altogether do not form a single structure comparable to the catholic church, or to a lesser extent the eastern orthodox communion. however, several different comparable communions exist within protestantism, such as the anglican communion, world communion of reformed churches, world baptist alliance, world methodist council and the world lutheran federation. regardless, 900 million is the most accepted figure among various authors and scholars, and thus is used in this article. note that this 900 million figure also includes anglicanism, as well as anabaptists, baptists and multiple other groups that might sometimes disavow a common "protestant" designation, and would rather prefer to be called, simply, "christian".