The Father sent the Son out of love, and the Son obeyed, and endured His Father's wrath out of love.
The "cup" that Jesus asked might be taken from Him was that of God's wrath. Not merely physical agony, but separation from God.
He took God's wrath off of us, by taking the sins of the world - our sins - on himself. He took the punishment we all deserve, and now we are made righteous through His blood.
That my friends, is true love.
(I don't know what it is about this picture that really struck me)
Hallelujah, what a Savior,
I owe everything to Him!
But death couldn't keep Him.