Answer:
People cannot always be judged by their affiliations.
Step-by-step explanation:
Being a member of the Nazi Party was not a desirable friendship trait for someone who was not a member of the same party. In the passage we are given two examples of people who, despite their membership in the party, are trustworthy people.
The first example is the unnamed man mentioned to have given away his membership by wearing a pin. It is said that despite this accessory he was not a Nazi at heart. The other example is Mr. Frank, a friend or at least close acquaintance of the author.