Look at anti abortionists.
"our god says they are evil so we destroyed the thing bringing evil here"
Anyone who shares the same religion would/should go "they didn't do anything wrong"
The crime was "firebombing a building and destroying property of the owner"
Not "Was the religion's beliefs so strong they had the right to destroy a building and shouldn't be held accountable"

If we allowed the argument " I did what i thought needed to be done" and that was all that was needed to be guilty/not guilty. I cant imagine the amount of folks that could or would be set free.

"My body said it was natural to take what i want from them"
"I didnt like them any my brain said i should get rid of them"
"I wanted it so i made them give it to me"

None of those should be a viable defense to committing a crime.