"And it is not only legitimate, but obligatory, that we should think of the saying in Mk. 10:45 which tells us that the Son of Man has not come into the world to be ministered unto (like the supposed lords of this world), but to minister; and not to minister partially or occasionally, like many of those whose real aim is to rule, but totally and exclusively, by giving His life for many, for the liberation of many, by becoming their λύτρον [redemption]. This is the determination of His historical existence. His body and blood, as it is impressively repeated (however we may have to interpret the different texts in detail) in the thanksgiving and giving and receiving which took place at the Last Supper with the disciples ( Mk. 14:22 and par.). In order that others may receive from Him and appropriate what is active and revealed in Him, He will not and does not offer up anything less than Himself, His body and blood: This is my body; And this is my blood. And He does this with thanksgiving, as the great act of His εὐλογία [blessing] and εὐχαριστία [thanksgiving]. To the same context (understood either in relation to the Lord's Supper or apart from it) there belongs also the passage in Jn. 6:53 that if we are to have eternal life we must eat His flesh and drink His blood. We may also think of the very curious saying to the woman in Bethany about anointing His body for burial (Mk. 14:8). But perhaps the most eloquent individual testimony is the quiet fact that when He called the twelve to be with Him, and to go out proclaiming Him with power to cast out demons, He also called Judas (who betrayed Him, as is noted in all the accounts, Mk. 3:13 and par.). Notice that it was He Himself who called him. And as the Gospels see it, He does not do this naively or in ignorance. He is not surprised by what Judas does later. He knows very well what he will do. He calls him with this in view. He makes (v. 14) even this man His apostle. He could hardly have integrated His self-offering more clearly into His life's work than by bringing His παραδούς [betrayer] into this orderly association with Himself."
- Karl Barth, CD IV.2, 258-259.