How do I write a one page narrative as a political opponent of Nazism in Germany?

I think you can go with this in a variety of ways. 
Obviously, I think that one of the most direct ways would be to try to call attention to
the fact that Hitler and the Nazis do not provide the best answer to Germany's
problems.  This might involve you writing as a supporter of Weimar democracy and the
idea that Germany's fragmentation can be addressed if all parties are seen as active
stakeholders in the process.  Indeed, you might borrow a sentiment from the Nazis in
suggesting that the Versailles Treaty was harsh.  Yet, it only underscores the
importance of all parties in Germany coming together and seeking to build consensus
across the board.  I think that you would probably speak out against the scapegoating
that Hitler was able to bank much upon in terms of tapping into German
resentment.

Perhaps you would argue that German nationalism
can be demonstrated without the demonizing effect of targeting individuals.  I think
that a political opponent of Nazism would be arguing that German history does not have
to trade off with individual rights.  In the end, you want to assert as a political
opponent of Nazi Germany that the Nazi approach will do more to isolate and target
Germany than raise it up.  There can be a way for German consensus to be demonstrated
without the element of targeting those who are different in order to consolidate power. 
It is a difficult position to articulate because few in Weimar Germany genuinely
understood the threat that Hitler posed until it was too late.