here is some data on the proportion of evangelical xtians & muslims in europe including the russia (which is around 10% muslim and rather populous remember) over the years….

1900 1970 2000 2025
Muslims, 2.3%, 2.7%, 4.3%, 5.1%
Evangelicals, 8%, 4.6%, 8.2%, 9.8%

there are several issues with the worry of the islamicization of the native white stock of the continent

1) it’s ahistorical, europe has had repeated swings between secularization and re-confessionalization since the enlightenment. the current swing to secularization may not be the “end of history”

2) 40,000 converts to islam per year is a hard number, but what about those who shift from mainline toward evangelical flavors of christianity? (which in england might be under the umbrella of anglicanism)

3) times change. the presumed moribund church of ireland (protestant) is now growing faster than the roman catholic church (mostly through conversion). see the irish census. straight line projections are really problematic, especially because of #1

4) the data thabet points to suggests that mainstream islam is similar in many ways to conservative christianity (see responses to moral issues by “religious americans”). i think it is plausible if europeans need something to feed their soul they would choose evangelical forms of christianity more often than islam since the latter is associated with insular ethnic communities.