denationalize

To transfer the control and ownership of an industry from government to private hands; to privatize.

To strip of nationhood; to cease to recognise, or allow to exist, as a nation.

Doubtless, in thus denationalizing the Tahitians, as it were, the missionaries were prompted by a sincere desire for good; […]

What does signify, however, is the assumption that evangelical missions introduce or maintain an alien culture and that they denationalize.