In the beginning, Adam and Eve were not created with the evil nature we see displayed in all of mankind. At the end of the sixth day of creation, God took pleasure in all He had made and pronounced it "very good," including Adam and Eve and the nature or the heart He placed in them. An evil heart cannot possibly be termed "very good." They were a blank slate, one might say, with a slight pull toward the self, but not with the strong, self-centered, touchy, and offensive heart that is communicated through contact with the world following birth.
Following Adam and Eve's creation, God placed them in Eden and instructed them on their responsibilities. He then purposefully allowed them to be exposed to and tested by Satan, who most definitely had a different set of beliefs, attitudes, purposes, and character than God. Without interference from God, they freely made the choice to subject themselves to the evil influence of that malevolent spirit. That event initiated the corruption of man's heart. Perhaps nowhere in all of Scripture is there a clearer example of the truth of I Corinthians 15:33: "Evil communications corrupt good manners."
Comparing our contact with Satan to Adam and Eve's, a sobering aspect is that God shows they were fully aware of Satan when he communicated with them. However, we realize that a spirit being can communicate with a human by transferring thoughts, and the person might never know it! He would assume the thoughts were completely generated within himself.
Following their encounter with the evil one, "the eyes of both of them were opened, and they knew that they were naked" (Genesis 3:7). This indicates an immediate change in their attitudes and perspectives. It also implies a change of character from the way God had created them, as they had indeed willingly sinned, thus reinforcing the whole, degenerative process.
This began not only their personal corruption but also this present, evil world, as Paul calls it in Galatians 1:4. All it took was one contact with, communication from, and submission to that very evil source to effect a profound change from what they had been. The process did not stop with them, as Romans 5:12 confirms, "Therefore, just as through one man sin entered the world, and death through sin, and thus death spread to all men, because all sinned." Adam and Eve passed on the corrupt products of their encounter with Satan to their children, and each of us, in turn, has sinned as willingly as our first ancestors did.
When we are born, innocent of any sin of our own, we enter into a 6,000-year-old, ready-made world that is permeated with the spirit of Satan and his demons, as well as with the evil cultures they generated through a thoroughly deceived mankind. In consequence, unbeknownst to us, we face a double-barreled challenge to our innocence: from demons as well as from this world.
Six thousand years of human history exhibit that we very quickly absorb the course of the world around us and lose our innocence, becoming self-centered and deceived like everybody else (Revelation 12:9). The vast majority in this world is utterly unaware that they are in bondage to Satan - so unaware that most would scoff if told so. Even if informed through the preaching of the gospel, they do not fully grasp either the extent or the importance of these factors unless God draws them by opening their eyes spiritually (John 6:44-45).