Before we can understand what sin really is in our personal experience, we need to look back to what happened when Adam and Eve sinned in the beginning of this world's history. What did God do in that emergency, when all of God's plans for the human race were being altered by the choices of His first created beings?
This is a puzzling verse, because we know that Adam and Eve did not die immediately. Yet God was very clear that immediate death would be the penalty for disobedience.
Adam and Eve did not die on the day that they sinned because the Substitute was placed between the penalty of death and Adam that very day. Jesus Christ took Adam's place, and personally paid the penalty for Adam's sin by dying on the cross.
There is a remarkable insight on what happened in the Garden of Eden in the following comments. "Why was not the death penalty at once enforced in his case? Because a ransom was found. God's only begotten Son volunteered to take the sin of man upon himself, and to make an atonement for the fallen race....The instant man accepted the temptations of Satan, and did the very things God had said he should not do, Christ, the Son of God, stood between the living and the dead, saying, 'Let the punishment fall on Me. I will stand in man's place. He shall have another chance'....As soon as there was sin, there was a Saviour....As soon as Adam sinned, the Son of God presented Himself as surety for the human race, with just as much power to avert the doom pronounced upon the guilty as when He died upon the cross of Calvary." S.D.A. Bible Commentary, vol. 1, pp. 1082-1085.
What we have learned is that Jesus' atoning death directly affected Adam and Eve and the whole human race. Jesus paid the penalty for Adam's sin, exactly as specified in Gen. 2:17. In doing this, Jesus gave Adam and Eve and the human race another chance to make different decisions about obedience and disobedience. The suffering and later death experienced by Adam and all of us was the result of sin , rather than the penalty of sin. The penalty was paid by Jesus Christ. Adam soon offered a lamb sacrifice, showing that he understood that the death penalty had been paid. But the result of sin (the curse of sin) has been a part of human existence to this day.
Here we see that death was not the direct result of their personal sins. They were not more guilty than others. The death they died was not the penalty of sin, but the result of sin, which has affected all who have lived on this earth.
Jesus is saying that blindness is not the penalty of sin, but is the result of sin's curse resting heavily on the earth and the human race. There is a clear distinction between the penalty of sin and the result of sin.
Notice that we have everlasting life when we believe, which can be today. However, even for those who believe and have everlasting life, they will still die and must be raised from the dead at Christ's second coming. Here we have a clear distinction between the first death, which Jesus called a sleep, and the second death, from which there is no resurrection. The first death is the result of sin pervading this earth, while the second death is the penalty for sin. While we cannot escape the results of sin, we can escape the penalty for sin by believing in God. This means that we can possess everlasting life even while we must die the first death. Thus the first death (and all suffering) cannot be the penalty for sin. Simply put, everlasting life means no second death, which is the penalty for sin. For further study, read 1 John 5:12,13.
Conclusion: This means that we must divide the basic idea of sin into two separate parts--evil, and guilt. Evil includes all the things which inherently result from sin, which includes suffering and death. Guilt includes condemnation and the second death. So we have two different consequences of Adam's sin. We have the curse--the inherent results of sin--that human beings, animals, and all nature experience which leads to the first death. We also have guilt, which only human beings experience, and which leads to the second death.
Now the atonement of Christ covers both of these consequences of sin, but in different ways. The atonement must deal with guilt by forgiving it, and with evil results by recreating and restoring what the curse of sin has done. In addition, forgiveness can be ours today, while recreation must wait until the second coming. Forgiveness is not needed for the results of sin, but only for the guilt of sin.
Thus the terms forgiveness, justification, righteousness, sanctification, salvation, and the gospel apply particularly to the guilt and penalty of sin. There is a fundamental difference between the result of sin and the penalty of sin. We are not guilty or condemned or lost because of being born into a sinful world. We suffer many results of Adam's sin, including physical defects and a fallen nature. But this is not the sin for which we are guilty or condemned. The sin for which we will be lost eternally comes from something else, which will be the subject of our next study.
This is why there is no guilt applied to a cat who tortures a mouse to death, while we hold a human being guilty for torturing someone. The cat is simply following its instincts--its fallen nature--without any knowledge of right and wrong, while human beings can be held guilty because of a conscious choice to do wrong. All animals and human beings suffer because of the results of sin, but they are not condemned automatically because of those results. Guilt applies only to moral responsibility for choices made. Guilt demands prior knowledge and willful rebellion.