Many ideas, but old translated texts also could spread because of the invention of cheap mass printed texts and books.
Germany, after Northern Italy, by that time had the most developed & productive citizenry living in free/independent cities. They can be seen as an early stage of bourgeous emancipated class.
The ideas of Luther & many others, & the emanzipation of this new productive class, led to the medieval "Peasant Uprising"/"Bauernkriege" in Germany against the Clergy and Nobitlity.
It must be mentioned that Luther sided with the "old powers" in these uprisings though.