Matthew 20:17-28 (NRSVCE)
Okay, as funny as I find that picture, there actually is something to be learned from today’s reading. The mother of the “sons of Zebedee” (that is, James and John) asks Jesus to place her sons on his right and on his left. The rest of the disciples get angry. Why do these two deserve such an honor, and we don’t? We were all chosen by Jesus! What makes them so special?!
But Jesus points out that all of them are misunderstanding what it means to be His disciples. They are still expecting Jesus to be the conquering king who will drive Rome and the wicked out of the Promised Land, establishing a New Israel! And once it’s conquered, Jesus will rule and place His loyal disciples in positions of power! This is not at all God’s plan for Jesus. In fact, their assumption is even more ridiculous when we can see that Jesus has just told them that he will be crucified. Jesus doesn’t come to lead an army in revolt against the Roman occupation, or even to wage a war of words and drive them out with some kind of “hearts and minds” campaign. He has come for a bigger purpose. He has come to “give his life a ransom for many,” to serve God and serve man in a way which man never could himself.
This life Jesus gives isn’t simply referring to the cross. Certainly that’s part of it, but it’s only a piece of the picture. This is articulated perhaps best by St. Anselm of Canterbury. He speaks of the debt we owe to God for our disobedience—for our sin. We owe everything to God, and ought to give him honor and praise for all things. But we failed to do that. We instead honored ourselves, as the disciples do here, seeking praise for ourselves when that praise is rightly given to God alone. We took what was not ours to take, and God’s infinite justice demands that debt be repaid. But how are we to repay that debt? God is infinite! How are we to give God the honor and praise he is due, when we are limited beings? The simple answer is: we can’t. 
But Jesus can, the Incarnate Son can. Not only through one grand gesture of obedience, namely, the cross, but everything Jesus did was for the glory of God alone. Where Adam failed, where we fail, Jesus succeeds. Every moment of His life was an act of service, both to God and to man, for the sake of man’s salvation. This isn’t some lofty moral point, this is the reality of the Gospel. If Jesus did everything in service, and we are to imitate Christ, then we ought to be doing all things in service as well. Jesus even uses the word “slave” which, despite the images which arise in our modern minds about the horrors of slavery, could not be closer to the truth! Jesus says “not my will but yours be done.” (Luke 22:42)
We talk about living lives of service all the time, but I don’t think we really take it to heart like we should. I know I struggle with it. Serving God in all things means serving our neighbors, and yet we see so many people in desperate need of service. Not only in remote places, but right here amongst us. Are these people not also made in the image of God? Are these people not deserving of our service? The answer from the Gospels is an emphatic “No!” These are the ones we ought to be focusing on, and yet are ignoring. Immediately before today’s reading, Jesus says “So the last will be first, and the first will be last.” (Matthew 20:16) And yet, like the disciples, we spend too much time trying to make sure that we are first in all things.
God calls us to be servants, just like His Son. For just as salvation is given in service, so too salvation is received in service.
 For more on Anselm's thoughts on this, look at Cur Deus Homo, particularly Book I, Chapters 20-25