This is an important passage which describes how you bring the ego and its world TO the holiness of truth, EXPOSE IT to the light, and it is SHONE AWAY by the light. Earth, which is part of the ego's world, is to be brought "to holiness", so that it is shone upon BY the light of holiness, which MAKES IT VANISH. Because the ego's world is made of darkness and illusions.
"The world you see is an illusion of a world and God DID NOT CREATE IT."
Earth, CANNOT, EVER, BE CONVERTED INTO HEAVEN, because it is UNHOLY and an ILLUSION. If it approaches the light, it will temporarily SEEM to become more holy because the light ITSELF is shining on and through it, and only the light is holy. The Earth will be shone away by eternity. Keeping it AWAY from the light maintains it in your mind and gives it "reality". Earth is never holy because it is not WHOLE. Holiness is only of Heaven. Eternity SHINES AWAY the world you made. This is A Course in Miracles.
"The Atonement does not MAKE holy. You were CREATED holy. It merely brings UNholiness TO holiness, or what you MADE, to what you ARE. The bringing together of truth and illusion, OF THE EGO AND GOD, is the Holy Spirit's only function. Keep not your making from your Father, for hiding it has cost you knowledge of Him, and of yourselves. The knowledge is safe, but wherein is YOUR safety, APART from it? The making of time, to TAKE THE PLACE of timelessness, lay in the decision to BE NOT as you WERE. Thus, truth was made past, and the present was dedicated to illusion. And the past, too, was changed, and INTERPOSED between what ALWAYS was, and NOW. The past that YOU remember NEVER was, and represents only the denial of what ALWAYS was.
Bringing the ego to God, is but to bring error to truth, where it stands corrected, because it is the OPPOSITE of what it meets, and is undone because the CONTRADICTION can no longer stand. How long can contradiction stand, when its impossible nature is clearly revealed? What disappears in light is NOT attacked. It merely vanishes, because it is not true. DIFFERENT realities ARE meaningless, for reality MUST be one. It CANNOT change with time, or mood, or chance. Its changelessness is WHAT MAKES IT REAL. This CANNOT be undone. Undoing is for UNreality. And this, reality WILL do for you.
Merely by BEING WHAT IT IS, does truth release you from everything that it is NOT. The Atonement is so gentle, you need but whisper to it, and all its power will rush to your assistance and support. You are not frail, with God beside you. But WITHOUT Him, you are nothing. The Atonement OFFERS YOU GOD. The gift which you refused, is held by Him in you. His Spirit holds it there FOR you. God has not left His altar, though His worshippers placed other gods upon it. The temple still is holy, for the Presence that dwells within it IS Holiness. "