Christianization

Christianization is a term for the conversion of non-Christians to Christianity.

Christianization is also a term used for "baptized paganism"

When referring to Northern Europe, the means of this conversion were chiefly mission directed towards monarchs and chieftains whos people then followed their conversion.

Crusades against the Wends, Balticum, and present-day Finland were also organized, although it's disputed how much these served a religious purpose or the power ambitions of kings, princes and noble bishops.