Jesus told His disciples that the cup of the Lord’s Supper was the new testament in His blood. But later, in the Garden, when He agonized over His fast approaching death, He prayed that the cup would pass from Him. He was in such agony over this that His sweat was like blood, falling down to the ground.
Put these things together. Jesus prayed that the new testament would not come to pass. Nevertheless – what an important word that is! Jesus Christ was obedient to the point of death because His Father willed it. Jesus therefore emptied Himself, taking the form of a servant. He did not cling to His own will, but rather subordinated His own will to the will of His Father in heaven. It was the Father who determined to bring you into fellowship with Himself by this means. Jesus Christ acknowledged the sovereign authority of His Father, and learned obedience through the things that He suffered, and saw clearly the joy that was set before Him.
But note carefully: that joy included you, sitting here now. The cup that is set before you now is therefore beyond all reckoning, beyond all price. Behold what manner of love is this, that we should be called children of God.