Before Adam and Eve sinned, they were naked but unashamed (Gen 2:25). This does not mean they were unaware of their nakedness. They were neither stupid or ignorant. It means they were innocent. There was no pride or lust for sin. They had no awareness of guilt or shame. All of creation was naked. The animals, birds, fish, and plants did not wear clothes. It was normal to be naked. The serpent promised Eve that if she ate the forbidden fruit, her eyes would be opened to knowing good and evil (Gen 3:5). In a sense it was true, but not the way he meant. He meant they would no longer need God to tell them what was right and wrong because they would be able to decide for themselves without God. Their eyes were opened, but not to some enlightenment outside of God. Their eyes were opened to the shame sin causes. That is how they "knew they were naked (Gen 3:7)." They had been naked all along, but were not ashamed because there was nothing to be ashamed of. Now there was. They tried to cover their shame with aprons made of fig leaves. Apron means belt or girdle, so their effort was not sufficient to cover their bodies, let alone their sin and shame. Adam and Eve were completely unfamiliar with death, because it is the result of sin (Gen 2:17, Rom 6:23), which had not happened yet. When you pull leaves from a tree, they die. It would not be long before their fig leaf aprons would be shriveled. All of their actions were typical for someone who is ashamed. They tried to cover it up and hide it. When God came into the garden, they hid (Gen 3:8). They experienced fear for the first time. When God spoke to them, they made excuses and passed the blame (Gen 3:12-13). God held them accountable, and drove them from the garden because He did not want them to live forever until He could rectify the sin problem (Gen 2:22-24).
Adam and Eve now had lost their innocence and had a conscience. The word conscience means joint knowledge or co-perception. God knew what sin would do, but they did not. He warned them, but they did not listen. Now they knew what God was talking about, but it was too late. They had no way to regain their innocence. Ever since then mankind has an innate awareness of his sinfulness. Jesus challenged the religious people of His day by saying that he who was without sin had the right to stone the adulteress to death (Jn 8:1-11). Their own conscience convicted them. Even those who are not familiar with God and the Bible have this, so they too will be held accountable (Rom 2:14-15). So is there any hope for man? Can he have his conscience cleared of evil? Can innocence be restored? The man who used the word conscience the most in the Bible was Paul. Before he was the apostle Paul, he was Saul, the persecutor of the church (Acts 7:58, Acts 8:1-3, Acts 9:1-20). If any Christian would have a struggle with a guilty conscience, it would be him. Yet he found that through the blood of Jesus Christ, his conscience was freed from condemnation (Acts 23:1, Acts 24:16, Rom 9:1, 2Cor 1:12, 2Tim 1:3, Heb 10:22, Heb 13:18). When the blood of Christ is applied to us in water baptism (Acts 2:38), not only are our past sins forgiven, but our conscience is freed (Heb 9:14, Heb 10:22, 1Pet 3:20-21). God no longer holds our past sins against us. Sometimes we still hold them against ourselves, but if we have truly repented, we do not have to be tormented by our past. When that voice of condemnation comes, we can answer it with the blood of Jesus Christ. It has been said that one way to describe justification is that it means God makes it just as if it never happened as far as the conscience and judgment are concerned. It does not erase the past, but it no longer has control over us spiritually.
Also, having a conscience does not only mean having awareness of past sins. It now also means being able to tell right from wrong as it is guided by the word of God. This is a good thing. Feeling bad when we do something wrong is not something to shun. What is dangerous is not feeling bad. The Bible speaks of having a conscience that is "seared with a hot iron (1Tim 4:2)." This phrase in the original language is the word cauterized. This is what happens when a burn is so bad that the nerves are destroyed. They no longer send a message to the brain the something is wrong. It might sound appealing to not bale to feel pain, but it is very dangerous. Pain is the body's way of telling the brain something is wrong. When that does not happen, there is no response to the danger. This can be fatal. Spiritually speaking, when our conscience no longer bothers us when we sin, we are in grave danger of hell. Ephesians 4:19 describes it as being past feeling. Our conscience can be our enemy when it tries to haunt us about the past, but it can also be our friend which leads us to repentance. Better yet, it can be the voice that warns us before we sin when it is under the influence of God.
The word innocent appears 38 times in the Bible, mostly speaking of innocent blood - people that were killed unjustly. We can have a clear conscience through the salvation of Jesus Christ. We can be free from condemnation over our past. We can live a life of holiness before God as we are empowered by His Spirit, and have innocence restored.