The answer is: He had made himself the Son of God

John 19:7 - The Jews considered the adoption of this title as blasphemy.

When Jesus stood before Pilate, the tension was palpable. For the Jewish leaders, calling Himself the Son of God wasn't just a slip of the tongue; it was an act of high treason against divine order – a move they deemed nothing less than blasphemy. In their minds, it challenged the very monotheistic beliefs that were foundational to their identity.

The term “Son of God” was loaded with history and implications. It peered into the heart of Jewish tradition and echoed back to King David, who is referred to as God’s son in the Psalms. When Jesus made His claim, He redefined sonship in a way that was welcome to many but threatening to the authorities.

In ancient cultures, titles meant everything, and the bold declaration of divine association rattled the cage of religious authority. Remember how often such proclamations resonated with the themes in many of the prophetic texts, where God’s chosen one would bring truth and justice? It's fascinating how the resonance of these claims created ripples throughout history.

Furthermore, understanding their role in this narrative sheds light on many similar accusations faced by reformers throughout the ages. Each call to shift the understanding of the sacred often comes with its own set of turmoil. Whether through stones being thrown, suggestions of heresy, or silence, the complexity surrounding the self-identification themes follow consistently throughout history.