Lutheranism spread into Scandinavia in the 16th century, when the monarchs of Denmark-Norway and Sweden converted. 

The Reformation of Denmark-Norway began in 1537 after Christian III, who had been openly Lutheran since hearing Martin Luther speak in 1531, ascended the throne. The first Lutheran Bible in Danish was published in 1550. In Sweden (then including Finland), the Reformation began with Olaus and Laurentius Petri, who lead King Gustav Vasa to Lutheranism. But Lutheranism was not made official in Sweden until 1593. The first Finnish New Testament was published in 1548.