Confession and Martyrdom
The defining episode of Thaddeus's life is his trial during the iconoclast persecution. By the synaxarion's account, his persecutors laid an icon of the Savior on the ground and stood him upon it, intending to present him as one who trampled the holy image. Thaddeus answered that he had been placed upon the icon against his will, and he denounced the impiety of the iconoclasts.
Enraged at his words, his tormentors beat him with cudgels, dragged him by the legs, and threw him outside the walls of the city. Though he appeared to be dead, he was still alive; a Christian took him into his home and tended his wounds. He survived three more days before dying. A parallel Western tradition records that he was scourged with one hundred and thirty lashes and died two days after being left for dead.