Washing feet in the ancient culture was as common and necessary as brushing teeth is today. But washing someone else’s feet was a task reserved only for the lowest slave. Feet-washing slaves had hit bottom in the socio-economic scale. In fact “in a household without servants,” Richard Bauckham writes, “everyone washed their own feet” (The Testimony, 192).

Jesus assumes the position of a low slave when he washes the disciples’ feet in John 13:1–20. The disciples were embarrassed by his act. It didn’t make sense. But what’s not to understand? The disciples had dirty feet and needed them cleaned. Yet there was meaning to the event that the disciples couldn’t perceive. In the middle of the narrative Jesus says, “What I am doing you do not understand now, but afterward you will understand” (v. 7).

Hold that thought.

If foot washing was the task of a slave, the cross was a unique threat to the slave class. Crucifixion was a Roman convention commonly reserved for rebellious slaves, a useful tool to prevent rebellion among the slave class, and a useful tool to make an example of lawbreaking slaves and any slaves connected to the guilty slave (see the story recorded by Tacitus in The Annals, 14.42-45).

Jesus’ foot washing act begins to make sense. Jesus takes the position of a slave, serves like a slave, washes the disciples feet like a slave, because ultimately he is preparing to die the degrading death of a slave (Phil. 2:7–8).

The disciples could not fully understand this point when Jesus lowered himself to his knees with a basin of water. This single act was significant for many reasons: here we find that no act is beneath the Christian; we find a model of Christian service to others; etc. But most significantly, in the foot washing we find a metaphor for the cross. The disciples could not see this, not here, not now. The full explanation for why Jesus washed their feet would only become clear after the substitutionary atonement of the Savior. Then they would understand that in the cross we find complete cleansing–head to toe–from all our sin.