The Holy Bible, in general, for there are many different versions, is a history of men who have seen God.  Moses is our first historian, and the first five books are credited to him.  He didn't personally witness anything in Genesis, so we are left to wonder where this history came from.  But Exodus is about Moses leading the descendants of the prophet Jacob, also known as Israel, out of Egypt and into the land of Palestine, where Abraham, Jacob's grandfather, lived centuries before.  The accounts of all three of these men revolve around their relationship with God.  The name of their god is Jehovah, or Yahveh in English, but is usually just called "The Lord" or the angel of the Lord.  In Genesis, chapter 18, the Lord and two other men appear to Abraham.  These are not spirits, but men in every aspect; Abraham hurries to bring water to wash their feet and food to assuage their hunger.  Abraham is about 100 years old, and his wife Sarah is about 90, so when the Lord tells Abraham that she will give birth in the next year, Sarah overhears them and laughs.   Never-the-less, she does give birth, and Isaac is born. 

Despite the belief of many Catholics and Protestants, the scriptural canon is not complete, and it is not closed.  God is not dead and he did not retire.  People can still testify of his works today.