"Kenosis" is derived from the Greek word "kenoo" which means "to empty." It is used in Phil. 2:7. The text of Phil. 2:5-8 is worth recording here.
"Have this attitude in yourselves which was also in Christ Jesus, 6who, although He existed in the form of God, did not regard equality with God a thing to be grasped, 7but emptied Himself, taking the form of a bond-servant, and being made in the likeness of men. 8And being found in appearance as a man, He humbled Himself by becoming obedient to the point of death, even death on a cross." (Phil. 2:5-8).
The kenosis theory states that Jesus gave up some of His divine attributes while He was a man here on earth. These attributes were omniscience, omnipresence, and omnipotence. Christ did this voluntarily so that He could function as a man in order to fulfill the work of redemption. This view was first introduced in the late 1800s in Germany with Gottfried Thomasius (1802-75), a Lutheran theologian.
Phil. 2:5-8 does not teach that Jesus gave up any of His divine attributes since it says nothing of those attributes. Instead, it is speaking of His humility that moved him, according to the will of the Father, to leave His majestic state in heaven and enter into the humble position of human nature.
There is, however, a problem the orthodox must deal with that the Kenosis theory seems to more adequately address. Take Mark 13:32 for example. In it, Jesus said, "But of that day or hour no one knows, not even the angels in heaven, nor the Son, but the Father alone." If Jesus knew all things, as is implied in His divine nature, then why did He not know the day or hour of His own return. The answer is that Jesus cooperated with the limitations of humanity and voluntarily did not exercise His attribute of omniscience. He still was divine but was moving and living completely as a man.
The Kenosis theory is a dangerous doctrine because if it were true, then it would mean that Jesus was not fully divine. If Jesus was not fully divine, then His atoning work would not be sufficient to atone for the sins of the world.
The correct doctrine is the Hypostatic Union--that Jesus is both fully God and fully man (Col. 2:9) and did not give up any divine attributes while as a man on earth.