dissenter:
(plural: ‘dissenters‘; pronunciation: the letters ‘diss’ rhyme with the letters ‘dis’ in “discuss” — for the right pronunciation, please click here)
a person who dissents;
(in old British usage & usually with a capital ‘D’ & in this context also ‘nonconformist’) a person who opposed the ways of the established Christian Church;
a dissident (next entry),

John McCain, US senior senator, known as a dissenter for opposing the policies of his own Republican Party
When Ms Morgan spoke about the unlawful practices of the institution openly, she was called a dissenter and dismissed from the service!
Religious dissenters are those who question the traditional ways, and argue that modern ideas should be included in the religious doctrines for the simple reason that we are living in the present world and the world has changed greatly over these thousands of years since the original Holy Books were written.
Political dissenters are normally those politicians who oppose the policies of their own particular major political party, and in most cases, these dissenters are pacified by the high command of the party by offering them important positions, but regarding some tough nuts, extreme measures, such as dismissing them from the party or, in most Asian countries, putting them behind bars on corruption or other scam charges, are taken!

