I'm fairly terrible at English, is this correct usage of a colon?
Bigotry unfortunately doesn’t just relate to opinions: it refers to intolerance towards ethnicities and beliefs
As punctuation is a matter of style, not grammar or usage, correct must be understood relative to the manual of style that you're using. I use the Chicago Manual of Style, which notes that a colon may be used to separate two clauses when the second clause provides an "illustration or amplification" of the first. Which seems to apply to your sentence.