creedbound
/ˈkriːdbaʊnd/Definitions
1. adjective
firmly or unshakeably convinced of a particular creed, opinion, or principle
“She was creedbound in her views on the environment and refused to compromise.”
2. noun
a person who is firmly or unshakeably convinced of a particular creed, opinion, or principle
“He was a creedbound individual who wouldn’t budge on his stance.”