Is the opposite of dangerous. Being informed helps people make better decisions, and on a macro scale it helps society progress by not basing the collecting decisions on erroneous or untruths ideologies. The example you gave is theoretically possible and it may have happened once a century but, the reality is that people that does not believe the religious belief of free-will, do not behave like that.

You gave an argument against free will based on Determinism, but there are other good and even better arguments IMO. Like the science-centrist arguments of Neuroscience , Psychological and the Evolutionary Arguments. Then there are the philosophical Arguments from Divine Predestination or Fate. There are still more but the fun is on the discovery.

“Feelings are like children, you can’t let them drive, but you can’t put them in the trunk.”

But I feel that one has a ¨spiritual parent¨:

“Educate a child so you don’t have to reprimand an adult.”

and a ¨spiritual sibling¨:

“If your only tool is a Hammer then every problem looks like a Nail.”