reveal, revelation

Definition:

The term "reveal" means to cause something to be known. A "revelation" is something that has been made known.

In the Bible, the term "reveal" is often used to describe how God has made himself known to people.
God has revealed himself through everything he has created and through his communication with people by spoken and written messages.
God also reveals himself through dreams or visions.
When Paul says that he received the gospel by "revelation from Jesus Christ," he means that Jesus himself explained the gospel to him.
The New Testament book "Revelation" is about God revealing events that will happen in the end times. He revealed this to the apostle John through visions.

Other ways to translate "reveal" could include, "make known" or "disclose" or "show clearly."
Depending on the context, possible ways to translate "revelation" could be, "communication from God" or "things that God has revealed" or "teachings about God." It is best to keep the meaning of "reveal" in this word.
The phrase, "where there is no revelation" could be translated as, "when God does not reveal himself to people" or "when God has not spoken to people" or "among people whom God has not communicated to."