It is often authoritatively claimed that the cup that Jesus drank was the cup of God’s wrath. In support, verses are quoted from the OT which refer to the cup of God’s wrath (e.g. Jer 25:15). Whilst it is true that the OT often refers to a cup of wrath, this is not the only kind of cup. We cannot ignore the broader definition of cup and its multiple use.
Throughout the Bible, the word “cup” refers both to a drinking vessel, and also as a symbol of our “lot” or “portion” which can be both good and bad. So it is that in the OT we find that cup may refer not just to wrath (Is 51:17) or horror and desolation (Ex 23:33) but to the Lord himself (Psalm 16:5,); to salvation (Psalm 116:13); an overflow of blessing (Psalm 23:5) or consolation (Jeremiah 16:7). In other words, there is no single “cup”, it is symbolic of whatsoever may fall in our way. We cannot simply extract one particular cup and apply it uniformly across every instance of the word.
So what of Jesus’ cup?
In the NT we see that Jesus is troubled as the time of his glory approaches. About to enter Jerusalem he again tells his disciples of his impending death at the hands of the chief priests and the scribes, how they will mock him and spit on him, and flog him and kill him (Mark 10:33-34).
Even while he is explaining this, James and John make an outstandingly arrogant request – to sit on his right and left when Jesus comes into his kingdom! (Mark 10:37). Mindful clearly of what he is about to endure, Jesus asks whether they can drink the cup he is about to drink. They assure him they can (Matt 20:22, Mark 10:38). And then, in response, Jesus confirms that they would indeed end up drinking the same cup as he (Matt 20:23, Mark 10:39).
Given Jesus’ direct testimony that James and John will also drink the cup he is about to drink, we have to conclude that Jesus is talking of the cup of suffering / rejection / persecution / death. What it cannot be is the cup of God’s wrath.
So as the hour approaches for his betrayal into the hands of sinners (Matt 26:45), Jesus prays for this cup to pass from him (Matt 26:39). Jesus has not already drunk the cup of suffering so we cannot claim that the narrative might be presenting us with a new or different cup. This cup has to be one and the same that Jesus talked of earlier as the cup he was about to drink.
We have no option then other than to conclude that Jesus is referring to the cup of suffering, and that James and John would one day also share in it.