When Jesus says, ‘I am thirsty,’ I don’t think he means physical thirst, because in the whole passion account we never once hear Jesus complaining about any of the physical torture and agony into which he is placed. He is blindfolded and beaten with fists of soldiers. He is scourged with a whip made with bits of metal and glass fragments tied into straps that are laid repeatedly across his back. There is a crown of thorns meanly pressed into his brow until he bleeds. Never once does he complain. Never once does he say, ‘It hurts.’
So when he says, ‘I am thirsty,’ he is saying, ‘I am thirsty with a thirst that every sinner deserves to experience forever.’ He means that he is going to hell, that he is now like the rich man in hell, with no one to bring him water.
In speaking of his thirst, perhaps Jesus is thinking of Psalm 22:
I am poured out like water,
And my bones are out of joint.
My heart is like wax;
it is melted within me.
My strength is dried up like a potsherd,
And my tongue cleaves to my jaws;
And Thou dost lay me in the dust of death (vv.14-15).
Jesus understands his thirst biblically. In fact, the larger context of Jesus’ remark about his thirst reads, ‘in order that the Scripture would be fulfilled, [Jesus] said, “I am thirsty.” Psalm 22 begins this way: ‘My God, my God, why hast Thou forsaken me?’ (v.1; quoted in Matt.27:46; Mark 15:34). This thirst is primarily physical but comes about because the Son of God has now been put into hell, a hell that he does not deserve. You and I deserve that unquenchable, unremitting, agonizing thirst because we have sought to fill our lives with anything and everything but him.
At the cross, Jesus asks the question, what do you thirst after? Throughout Scripture, thirst is a metaphor for a deep, inward spiritual emptiness and need. Without God we will die, because the Bible says that what we most thirst for and need at the center of our lives is not stuff but God. The question always is, what do I drink to fill that deep and profound thirst within me? (pp.82-83).
“I am Thirsty” by Joseph “Skip” Ryan, in Jesus, Keep Me Near the Cross, ed. by Nancy Guthrie; Crossway, 2009.