Copied from another thread:
How are beliefs harmful to others?
Since it`s my quote you`ve pasted I`ll have a go at explaining.
The Spanish Inquisition.
The KKK, National Alliance, Christian Identity.
The Crusades.
Sharia Law
Soviet Style communism.
Abstinence Education
Those are just a couple of examples of systems of belief that have actively caused harm to people.
On a smaller scale considering the post the paste was taken from.
The Catholic Diocese in my area decided awhile back that Abstinence Only ED was what was to be taught in our public schools and through a series of backroom maneuvers actually instituted it before the sane segment of my community caught on and put it down.
This Catholic belief almost terribly harmed the children in my community.
I have a Muslim co-worker who has no problem beating his wife because he believes Allah tells him it`s ok.
I have another co-worker who believes finding money and not returning it when you can is perfectly ethical and harms no one.
I have numerous acquaintances who believe the black race is intellectually inferior to other races and has no problem with discrimination against blacks.
I could go on but I "believe" the answer to your OP is obvious.
What we believe shapes the very world we live in.
It`s important.