Word that means "describing a group of people based on the action of an individual" [duplicate]
"All Muslims are terrorists" does not differ in its logic from "All lawyers are thieves" or "Everyone likes chocolate." All are over-generalisations.
If you wish to add emotion and imply a derogatory sense, you can call such people bigots:
OED:
2. bigot (n.) b. In extended use: a fanatical adherent or believer; a person characterized by obstinate, intolerant, or strongly partisan beliefs.
1992 Face June 5/2 The way to defeat the bigots is to not let them create hate inside you.