Man as a human being or soul, came under the influence and control of the flesh. The soul was then damaged and became the self . Although we cannot find a verse which says that man's body is Satan, there is a verse which clearly indicates that the fallen soul, the self, is Satan. We have already seen that Satan as sin is in the body. Now, Matthew 16 shows that Satan not only has ground in the soul, but is also mingled with the soulish self.
Self is the nature of the soulish life, and the soulish life is the life of the soul, the person.
It means that self and Satan are mingled as one. Therefore, the very nature of the soulish life, which is the life of the soul, the man himself, is the satanic self. The life of the soul is soulish, and the nature of this life is the satanic self. After Satan came into man's body, he used it as a base to invade the soul and even mingle himself with the soul. Through the mingling of Satan with the soul, the soulish life has become the ugly, sinful ego.