Begging the Question is a logical fallacy that occurs when an argument implicitly assumes its conclusion.
"How do you know the Bible is correct?"
"Because it was written by God."
This begs the question "How do you know that god wrote it?" (Note that if the Christian answers the latter with "Because it says in the Bible that he did" then this is an example of circular reasoning.)
Often, people say "beg the question" when they really mean "raise the question", e.g., "You say that theism makes more sense then atheism, but that just begs the question of which religion I should join."
"Begging the question" means "assuming one's conclusion". This is not the same as raising further questions.