It's the root of many English words, including:
* Credit: Belief in someone's ability to repay a debt.
* Credential: Something that provides proof of a person's qualifications or authority.
* Credible: Believable or trustworthy.
* Incredible: Unbelievable, amazing.
* Credence: Belief or trust.
* Creed: A statement of belief, especially a religious one.
* Credulous: Tending to believe things too readily.
So, whenever you see "cred" in a word, it often points to a concept related to belief, trust, or faith.