This coming Sunday is the 29th Sunday in Year B of the lectionary cycle. It is a familiar story in which James and John seek glory: ““Grant that in your glory we may sit one at your right and the other at your left.” (Mark 10:37). In our previous post, Jesus has answered them “You do not know what you are asking. Can you drink the cup that I drink or be baptized with the baptism with which I am baptized?” It would be good to know Jesus’ tone of voice when he responds. Is it exasperation caused by their continuing blindness? Is it said as a tired sigh but with a willingness to again engage them and lead them to a deeper understanding and awareness? Does it have an edge? It might well be the simple inquiry to uncover what they understand: “Can you drink the cup that I drink or be baptized with the baptism with which I am baptized?”
There are several lines of interpretation regarding Jesus’ reply. Some scholars hold that the images offered (“drink” and “baptism”) do not hold the same significance for the disciples as they do for Jesus. In this line of thought, the cup and baptism point to Jesus’ voluntary obedience unto death for the sins of humanity; whereas, the images suggest the disciples’ moral participation in Jesus’ passion. [Lane, 379]. But the construct of the sentence is in the present tense. In other words, right at his moment, Jesus is drinking and being baptized. This seems to point to something other than a future moral participation in the Passion.
The “cup” (potērion) plays a prominent role in the passion. The cup of wine represents the blood Jesus will shed to establish the new covenant (14:24). Jesus’ prayer to be spared the cup if it is God’s will makes the cup stand for all the suffering of the passion (14:36). In the OT, the word for “cup” is used metaphorically to refer to divine wrath or punishment in response to sin and rebellion (Pss 75:9; Isa 51:17; Jer 25:15–16; Ezek 23:33). Thus Jesus might be said to drink the “cup” as the sacrificial victim whose death atones for the sinfulness that merited God’s wrath (Rom 3:24–26; 2 Cor 5:21; Gal 3:13). But that view does not explain how the disciples can drink the cup. While their participation is not redemptive as is Jesus’ they are being asked if they can accept the same kind of suffering that Jesus now faces.
The use of “baptism” in parallel with “cup” indicates that it is also a metaphor for suffering. Old Testament references to waters overwhelming the sufferer in lament psalms may have provided the origin for this metaphor (Pss 42:8; 69:3). In popular Greek usage the vocabulary of baptism was used to speak of being overwhelmed by disaster or danger. The two images together reinforce the suffering to come that Jesus will face and that his disciples will also eventually face. Hence the question is “Can you drink the cup that I drink or be baptized with the baptism with which I am baptized?” To share one’s cup was a recognized expression for sharing his fate.
Juel [Mark, Augsburg Commentaries] suggests a sacramental image with “cup” and “baptism”:
“… While the term “baptism” could be employed in Greek literature to speak about being overwhelmed by catastrophe, the awkwardness of the phrase may suggest that it is chosen because of its place in the church’s technical vocabulary. In Paul’s letters, the rite of Christian Baptism is interpreted as sharing Christ’s death (Rom. 6:1-5; in Ephesians 2 and Colossians 2, sharing in his resurrection as well).”
“It is tempting to speculate that the images of cup and baptism are chosen here in light of Christian ritual. Understanding Jesus’ words to James and John does not require locating them within Christian tradition. The images of cup and baptism are sufficiently clear by themselves. In view of that tradition as it is known elsewhere in the New Testament, however, it is tempting to speculate that Jesus’ words represent an effort to understand more deeply what is implied in the church’s sacramental practices. In Baptism and the Lord’s Supper, the faithful share Christ’s destiny. That is precisely what James and John want — and it is precisely what they fail to understand. They know that the kingdom will come; what they do not grasp is how and at what cost. [pp. 146-7; found in Stoffregen]”
They may not know the way or the cost, but as Perkins  notes: “Jesus’ prophecy concerning the martyrdom of James and John reminds the reader that the failures of the disciples during Jesus’ lifetime are not the final word about their faithfulness as followers of Jesus. Although they will run away during the passion, these same disciples will later share the suffering of Jesus.”