That depends on how you define "belief". My definition is that a "belief" is a representation in your brain that you use to make predictions or judgments about reality. The emotion experienced in response to thinking of the prohibited or "icky" behavior is the direct functional expression of that belief.

The definition as you actually write it here isn't bad. The conclusion just doesn't directly follow the way you say it does unless you modify that definition with some extra bits to make the world a simpler place.