Worst crime isn't always something that's a crime in the legal sense.
Forcing your beliefs on others in ways that they can't resist -- or as another phrasing of it, using your free will to take away another's free will (or perceived free will, since I don't entirely believe free will exists). -- basically every type of crime one person could do to another living thing.
I define "beliefs" for that statement it includes "belief that relations with family members or children is right", "believing that murder is right", "passing laws for one church that all people will have to follow", "belief that you should screw over everyone you see, because they aren't you", etc.
NOT things like "trying to convert someone from one belief system to another" through verbal means where the person can freely choose not to change if they desire (without any repercussions).