Although Adam and Eve had been given an entire paradise by God, they wanted even more. Their sin was motivated by selfishness, as is true for most sins. They turned against God, and then hid themselves (Gen. 3:8). This created distance between God and man. This is the fall into sin or fall of man: the way sin came into the world.
God has given man free will. You can only love someone when you have free will. We can choose God, but we can also reject him, resulting in sin. Because of original sin, the sin that we inherited from Adam and Eve, we humans are no longer perfect as we were intended by God in the creation. By coming to earth, Jesus wanted to change that situation by instituting the Sacrament of Baptism.
