Forrest Gump made the adage, “Stupid is as stupid does“, popular; however, it came from an old adage that says, “Handsome is as handsome does.” This saying appears in J.R.R. Tolkien’s “The Lord of the Rings” and in Herman Melville’s “Billy Budd,”. It can be traced as far back as the 14th Century. However, that ignorance does as “belief dictates”, has been with a man throughout history.
The phrase more often than not is attached to religion.
One only needs mention names like Crusades, Inquisition, Cathars, and witches to see the insanity of religious beliefs gone awry. In addition, I didn’t mention Newton, Copernicus, and Kepler and a long list of scientists that the church persecuted or killed in the name of certain “doctrinal beliefs”. It’s odd and sad at the same time that Christianity warns and teaches against IDOLS, and yet they IDOLIZE many doctrines: even doctrines that have been proven wrong, illogical, and scientifically in error.
People will kill (and have) to protect the SACRED mental COWS!
I wonder which is worse. Is it more heretical to hold on to literal sacredness of cows as is the case in India or holding on to mental sacred cows as many religions embrace? Have you ever wondered about that? 
Once firmly ingrained (often times as infallible), a BELIEF system takes over the controls of the brain and establishes it’s identity in the ego state of that particular belief. Then the power of the misguided belief ignores any evidence, to the contrary. It’s akin to rescuing a woman from a physically abusive relationship only to see them NEED to go back into it.
People simply will not question a sacred holy cow, nor will they let anyone else hold on to any other belief system to the contrary. Nothing short of murder, and history shows even that’s not taken off the table of possibilities, can be applied to bring the reprobate, heretical, and infidel back into agreement with……with THEIR belief system.
Unfortunately, ignorance does as the belief dictates.
Fortunately, God’s grace is sufficient!
In the last four years most of my “sacred cows” ended up as “hamburger”. Thank you God!