Take just a moment to try to get in the mind of Jesus’ audience in this passage. In the US in 2019 you’re rarely more than a few minutes from what amounts to an endless supply of water, and folks only die of dehydration from freak accidents. But in Jesus’ context this kind of opulence and security was entirely unknown. Water was an intensely precious commodity. Access to it was controlled and closely guarded; the old city of Jerusalem had a heavily fortified well to ensure access during times of war. And supply wasn’t guaranteed; wells and rivers could run dry in a drought. Jesus’ audience didn’t just appreciate water, they worked to get it, waited for it, dwelled on it, stayed close to it, and worried over it’s absence.
This is the emotional backdrop for the ceremony that Jesus interrupts in John 6:37. On the great day of the feast of booths the high priest would walk with a procession down to the pool of Siloam to take a pitcher of water, then march it back to the temple to pour it by the altar. This ritual pouring was meant to remember and celebrate times that the Lord had provided water for Israel, and to anticipate his provision in the coming year. It was right in the middle of this that Jesus stood up to announce to everyone in attendance that he was the real answer to their thirst.
But of course, in Jesus’ fashion, he wasn’t talking about physical thirst or elemental water. This thirst is a soul-level thirst reminiscent of David’s language in the Psalms, “As a deer pants for flowing streams, so pants my soul for you, O God. My soul thirsts for God, for the living God.” (Psa. 42:1-2a) This thirst isn’t a desire for absolution, for only being clean or right or whole in and of itself, but a thirst for the one who makes us clean and right and whole. It’s a thirst for God himself; Jesus is the Water of Life. And he says here that believing in him produces a source of this water in us, an endless supply of nourishment and sustenance welling up by the Spirit that no drought can compromise and no army can capture.
Now of course all this was met with mixed reviews; see 6:40-52. Some were intrigued, some were impressed, and some were offended. Some were able to make some sense of what Jesus was saying, and some tuned him out because he couldn’t possibly been taken seriously. These are the same reactions Jesus’ claims get to this day. Some would hear him out and some would call him foolish (Acts 17:32). From Jesus’ teaching in this passage we can see that blessed is the one who will admit their thirst and come.