I don't mind it when people are very confident or even completely certain of their political beliefs, but they lack credibility to me when they don't have a good understanding of what the other side actually believes or understand their rationale for having certain beliefs.

Personally speaking, I see a lot of criticism of libertarians or conservatives that boils their motivations purely down to hatred or greed or some other Saturday Morning Cartoon Villain level motivation.

You can have a conversation with somebody who is certain of their beliefs but at least tries to understands the other side's motivations.