Democracy does not imply that a political party cannot be banned. Nazi party is forbidden in many countries that are usually considered democratic or at least flawed democratic (democratic formally, but not in effect).
Democracy in contemporary context also does not mean direct democracy, it means representative democracy. That's why banning a party that has overwhelming popular support can still be democratic, if it is done lawfully by democratically controlled institutions (via regular and free elections). Dissent of the people for a specific decision or policy does not have legal power in standard democracies unless a special mechanism is invoked, such as referendum with the power of law (whose invocation the president or representatives have to agree on, details depend on country).
This. Why does everyone think banning a party MUST be antidemocratic? If it can be proven that AfD is supporting Nazi views for example (which I am convinced many of its leaders are), then it's illegal in Germany and should be banned. Why would a party be above the law?
But scrutiny must work both ways, they should only be banned after due process.
> Why does everyone think banning a party MUST be antidemocratic?
Probably because those "everyone" (in fact, a big portion of population) wants to have that party that the other side wants to ban, and there is chance it could happen. So they try to defend it preemptively by suggesting any banning in general would not be democratic (which is probably not true).
Another reason is that in recent history, most if not all German governments banning parties either were undemocratic, or turned out to dismantle democracy.
Democracy in contemporary context also does not mean direct democracy, it means representative democracy. That's why banning a party that has overwhelming popular support can still be democratic, if it is done lawfully by democratically controlled institutions (via regular and free elections). Dissent of the people for a specific decision or policy does not have legal power in standard democracies unless a special mechanism is invoked, such as referendum with the power of law (whose invocation the president or representatives have to agree on, details depend on country).