Whenever I read that there are over a billion Muslims in the world, I can't help wondering how many fewer there would be if people in the Muslim world were freely allowed to abandon Islam without fear of torture, imprisonment and social ostracism.
The Declaration of Independence notes a similar dynamic very well:
Prudence, indeed, will dictate that Governments long established should not be changed for light and transient causes; and accordingly all experience hath shewn, that mankind are more disposed to suffer, while evils are sufferable, than to right themselves by abolishing the forms to which they are accustomed.