A Buddhist Monk walked up to a hot dog vendor in Manhattan.  A sign on the vendor's cart said "Hot Dogs - $5".  The monk said to the vendor, "Make me one with everything".  Seeing the irony in the request, the vendor obliged, served the condiment covered dog, and took a $10 bill from the monk.  
After a few moments of deafening silence, the monk asked for change of his $10 bill, the vendor replied calmly, softly, with a knowing smile, "Change comes from within".

The idea of being one, or "at one" with anything or everything is really an odd idea to me as a Course student.  It seemed clear to me that I do not need to be one with anything that I already AM.

"The Kingdom of God is within you", is an oft quoted Biblical phrase, which if properly understood makes it abundantly clear that everything, perhaps equally written as every thing, is within you.   If I am everything, what is there left for me to be one, or at one, with?

Jesus said years ago, "Be ye therefore perfect, as your Heavenly Father is perfect."  What he was saying was not to change into something perfect, or become perfect, but to BE perfect exactly as the ONE that created you exactly like Himself.  He was not saying this is something we should do, or work toward, or eventually be, but recognize it is what we ARE NOW.

Namaste.

Original Extracted notes below

• The purpose of the Atonement is to restore everything to you; or rather, to restore it to your awareness.
• The Atonement is the only defense that cannot be used destructively because it is not a device you made.
• The Atonement was built into the space-time belief to set a limit on the need for the belief itself, and ultimately to make learning complete.  The Atonement is the final lesson.
• Atonement is the device by which you can free yourself from the past as you go ahead.
• Until the Atonement is complete, its various phases will proceed in time, but the whole Atonement stands at time's end. 
• The Atonement is a total commitment.
• The Atonement is the guarantee that they [you] will ultimately succeed. [at healing the separation]
• The miracle is the means, the Atonement is the principle, and healing is the result.
• The kind of error to which Atonement is applied is irrelevant.  All healing is essentially the release from fear. 
• I have emphasized that the miracle, or the expression of Atonement, is always a sign of respect from the worthy to the worthy.  The recognition of this worth is re-established by the Atonement.  It is obvious, then, that when you are afraid, you have placed yourself in a position where you need Atonement.  You have done something loveless, having chosen without love.  This is precisely the situation for which the Atonement was offered.  The need for the remedy inspired its establishment.  As long as you recognize only the need for the remedy, you will remain fearful.  However, as soon as you accept the remedy, you have abolished the fear.  This is how true healing occurs.
• The lamb "taketh away the sins of the world" in the sense that the state of innocence, or grace, is one in which the meaning of the Atonement is perfectly apparent.  The Atonement is entirely unambiguous.  It is perfectly clear because it exists in light.  Only the attempts to shroud it in darkness have made it inaccessible to those who do not choose to see.
• The Atonement is therefore the perfect lesson.  It is the final demonstration that all the other lessons I taught are true.  If you can accept this one generalization now, there will be no need to learn from many smaller lessons.  You are released from all errors if you believe this.
• When you feel guilty, remember that the ego has indeed violated the laws of God, but you have not.  Leave the "sins" of the ego to me.  That is what Atonement is for.  But until you change your mind about those whom your ego has hurt, the Atonement cannot release you.  While you feel guilty your ego is in command, because only the ego can experience guilt.  This need not be.
• What fear has hidden still is part of you.  Joining the Atonement is the way out of fear.  The Holy Spirit will help you reinterpret everything that you perceive as fearful, and teach you that only what is loving is true.  Truth is beyond your ability to destroy, but entirely within your ability to accept.  It belongs to you because, as an extension of God, you created it with Him.  It is yours because it is part of you, just as you are part of God because He created you.  Nothing that is good can be lost because it comes from the Holy Spirit, the Voice for creation.  Nothing that is not good was ever created, and therefore cannot be protected.  The Atonement is the guarantee of the safety of the Kingdom, and the union of the Sonship is its protection.  The ego cannot prevail against the Kingdom because the Sonship is united.  In the presence of those who hear the Holy Spirit's Call to be as one, the ego fades away and is undone.
• Atonement is not complete until you join it and give it away.
• The purpose of the Atonement is to save the past in purified form only.
• Excluding yourself from the Atonement is the ego's last-ditch defense of its own existence.  It reflects both the ego's need to separate, and your willingness to side with its separateness.  This willingness means that you do not want to be healed.
• The Holy Spirit begins by perceiving you as perfect.  Knowing this perfection is shared He recognizes it in others, thus strengthening it in both.  Instead of anger this arouses love for both, because it establishes inclusion.  Perceiving equality, the Holy Spirit perceives equal needs.  This invites Atonement automatically, because Atonement is the one need in this world that is universal.  To perceive yourself this way is the only way in which you can find happiness in the world.  That is because it is the acknowledgment that you are not in this world, for the world is unhappy.
• The curriculum of the Atonement is the opposite of the curriculum you have established for yourself, but so is its outcome.  If the outcome of yours has made you unhappy, and if you want a different one, a change in the curriculum is obviously necessary.
•  Atonement is for all, because it is the way to undo the belief that anything is for you alone.
• You have a part to play in the Atonement, but the plan of the Atonement is beyond you.
• The Atonement is a lesson in sharing, which is given you because you have forgotten how to do it.
• ...you cannot abide in peace unless you accept the Atonement, because the Atonement is the way to peace.
• The Atonement is not the price of your wholeness, but it is the price of your awareness of your wholeness.
• The Atonement is but the way back to what was never lost. 
• The acceptance of guilt into the mind of God's Son was the beginning of the separation, as the acceptance of the Atonement is its end.
• This world is a picture of the crucifixion of God's Son.  And until you realize that God's Son cannot be crucified, this is the world you will see.  Yet you will not realize this until you accept the eternal fact that God's Son is not guilty.  He deserves only love because he has given only love.  He cannot be condemned because he has never condemned.  The Atonement is the final lesson he need learn, for it teaches him that, never having sinned, he has no need of salvation.
• As long as you believe that guilt is justified in any way, in anyone, whatever he may do, you will not look within, where you would always find Atonement.  The end of guilt will never come as long as you believe there is a reason for it.  For you must learn that guilt is always totally insane, and has no reason.  The Holy Spirit seeks not to dispel reality.  If guilt were real, Atonement would not be.  The purpose of Atonement is to dispel illusions, not to establish them as real and then forgive them.
• Those who accept the Atonement are invulnerable.  But those who believe they are guilty will respond to guilt, because they think it is salvation, and will not refuse to see it and side with it.
• The Atonement was established as the means of restoring guiltlessness to minds that have denied it, and thus denied Heaven to themselves.
• The Atonement is so gentle you need but whisper to it, and all its power will rush to your assistance and support.
• The Atonement is in time, but not for time.  Being in you, it is eternal.  What holds remembrance of God cannot be bound by time.
• Be not separate from me, and let not the holy purpose of Atonement be lost to you in dreams of vengeance.  Relationships in which such dreams are cherished have excluded me.
• Atonement is for you.  Your learning claims it and your learning gives it.
• Healing and Atonement are not related; they are identical.  There is no order of difficulty in miracles because there are no degrees of Atonement.  It is the one complete concept possible in this world, because it is the source of a wholly unified perception.  Partial Atonement is a meaningless idea, just as special areas of hell in Heaven are inconceivable.  Accept Atonement and you are healed.  Atonement is the Word of God.  Accept His Word and what remains to make sickness possible?  Accept His Word and every miracle has been accomplished. 
• The offer of Atonement is universal.
• Atonement is received and offered.