They seem like a different race to me and I make sure never to get into disagreements with them, because any puny thing I say gets dashed on the rocks of their robust, shouty certainty.
The quote expresses the speaker's perception of a certain group of people as distinctly different, almost alien, highlighted by their strong conviction and assertiveness. This feeling of separation leads the speaker to avoid conflicts with them, fearing that any opinion they express will be easily dismissed or overwhelmed by the others' dominating confidence.
This dynamic reflects a broader commentary on how differing personalities can influence interactions and communication. The speaker’s reluctance to engage in disputes illustrates a struggle between self-expression and the challenge of confronting those who exhibit overwhelming certainty in their beliefs.