See when we were born dead in sin Christ was already surety and responsible for our condemnation, as soon as it occurred in Adam, God looked to Christ to satisfy Justice for it.
		
		
	 
When we personally as individuals, were born dead in sin, Jesus had not only been our Surity, Responsible for Suffering the Punishment that our Guilt deserved for sinning against the Thrice Holy, Eternal, and Infinitely Perfect, Creator God of the Universe, but Jesus had already done so, as we know.
We're saying that God Looked to Jesus, in Eternity Past, and that that is when 
"God Will Provide Himself a Lamb", Genesis 22:8.
When?
"the Lamb Slain from the Foundation of the World", Revelation 13:8.
	
		
	
	
I believe, in my Father's House are many Mansions, where Jesus has Gone to Prepare a Place for His Elect and if it were not so, He would have told us, and that was by The Determinant Council and Foreknowledge of God, the same as Jesus' Crucifixion, and that both of those things were Planned and Agreed upon from Eternity Past.
Why? Because, God could not just Create a 'being' like the Elect Angels, who were Confirmed in their sinless State, or some robot-like creature to Commune with Him in Heaven Forever, so He Knew that the 'being' He Created to spend Eternity in Heaven Worshiping Him, would have to be Made Mutable, with the ability to change from Obeying His Soveriegn Commands, to disobeying them.
And, inevitably, that Created 'being' that He Made Mutable, whether it was Adam, or if it had been you or I, eventually changed from Obeying Him, and that cast that 'being', and the entire Human Race as it turned out, into a Condemned State of sin.
Then, once His Created 'being' was Condemned, there would be no way for those 'beings' to enjoy the Pleasures of Heaven with Them, apart from Him having a Plan in Place, from Eternity Past, to Make Provision for those souls of His Choosing, to be Granted Forgiveness of their sins. 
Thus, we have seen that The Eternal Covenant of Grace for the Absolute Perfect Accomplishment of the Salvation of those God Chose, 
"according to the Good Pleasure of His Own Will" AND 
"the Riches of His Grace", as we see in 
Ephesians 1:  
3; "Blessed be the God and Father of our Lord Jesus Christ, Who hath Blessed us with all Spiritual Blessings in Heavenly Places in Christ: 
4; "According as He hath Chosen us in Him before the Foundation of the World, that we should be Holy and without Blame before Him in Love: 
5; "Having Predestinated us unto the Adoption of children by Jesus Christ to Himself, according to the Good Pleasure of His Will, 
6; "To the Praise of the Glory of His Grace, wherein He hath Made us Accepted in the Beloved. 
7; "In Whom we have Redemption through His Blood, the Forgiveness of sins, according to the Riches of His Grace;"
And, as we know, if this could have been Accomplished any other way, God would not have Sent His Son to be Executed and Die the Cruel, Lingering Death of Crucifixion. 
But He did.
Why? was this 
"the Good Pleasure of His Own Will"?
There was no other way for this Prayer of Jesus to be Answered.
In 
John 17:24; "Father, I Will that they also, whom Thou hast Given Me, be with Me where I Am; that they may Behold My Glory, which Thou hast Given Me: for Thou Lovedst Me before the Foundation of the World."
And who else, again, did God Love, besides Jesus? 
"The LORD hath Appeared of Old* unto me, saying, Yea, I have Loved thee with an Everlasting Love: therefore with Lovingkindness have I Drawn thee." Jeremiah 31:3.
*or '
from Everlasting', the same as His Love. 
"Jacob, have I Loved", Romans 9:13
That is the only way for God to have a 'being' Beholding the Glory of His Son and BE WITH JESUS WHERE HE IS, FOREVER, to share with Them the Complacency and Delight The Triune Godhead has had, FOREVER.
"that they also...be with Me Where I Am."