How can the Protestant Reformation be considered a nationalist movement?

I see a couple of ways that you can argue this, even
though I am not at all sure that I agree with them.

First
of all, Germany was split into many little kingdoms during those days.  You could say
that each of these was a nation that could be nationalist.  Martin Luther was supported
by various rulers of these little kingdoms.  They could use the new religion as a way of
creating solidarity in their nations against
others.

Second, the Catholic Church is run from Rome.  You
can argue that it is nationalist to have Germans push for a religion that they
themselves control.  Since Lutherans did not obey any outside authority, you can say
they were nationalist.