Sin is a departure from the law of our being. The command of God to man is, "Be fruitful, and multiply, and replenish the earth, and subdue it; and have dominion over the fish of the sea, and over the birds of the heavens, and over every living thing that moveth upon the earth." The creatures of land and sea represent states of mind and they all are contained in the consciousness of every man. Any failure on our part to exercise this dominion is a falling short, or a "sin."
The "eternal sin," or unpardonable sin, referred to by Jesus in Mark 3:28-30, is the belief that God is the creator of disease or inharmony of any nature. This belief is called an "eternal sin" because that which is eternal is abiding. So long as man abides in the conviction that God causes him to suffer, he closes his mind against the inflow of God's gifts of health, peace, and harmony. Man's sins are forgiven when he ceases to sin and opens his mind to the fact that he is heir only to the good.