I got a really good answer to a similar question I posted back in October from u/Philip_Schwartzerdt -- not to discourage further discussion, but do check that out.

There are some really good books about this, because we have just passed the 500th anniversary of Luther's 95 Theses. I really enjoyed the book Brand Luther by Andrew Pettegree. It shows how Luther never expected things to unfold the way they did-- mainly because the spread of the printing press! Very interesting.