The book of Genesis is the first book of the Bible. It portrays the beginning of life on earth, indeed the start of everything that is. God, in a free act of love created the world. "In the beginning... " the world was far different from the one we know today. All of creation was in perfect harmony with the Lord. We don't often think of it this way, but before the first sin, the entire world was a temple in which mankind worshiped the one true God. Man fully possessed original goodness and original justice. Then Adam sinned and this was lost.
For one thing, the world at large stopped being a temple. It became necessary to build a temple in which God could be worshiped. Furthermore, man had to sanctify or purify himself before entering this sacred space. This was not necessary before the Fall. More in our next Genesis post.