Exiled at least three times and eventually arrested, Arnold was hanged by the papacy; his remains were burned posthumously and the ashes thrown into the River Tiber.

Though he failed as a religious reformer and a political leader,[2] his teachings on apostolic poverty gained currency after his death among "Arnoldists" and more widely among Waldensians and the Spiritual Franciscans, though no written word of his has survived the official condemnation.

He called on the Church to renounce its claim and return ownership to the city government so as not to be tainted by possession—renunciation of worldliness being one of his primary teachings.

[8] Arnold stood alone against the church's decision after Abélard's capitulation; he returned to Paris, where he continued to teach and preach against Bernard.

Having returned to Italy after 1143, in 1145 Arnold made his peace with Pope Eugene III, who ordered him to submit himself to the mercy of the Church in Rome.

Arnold sided with the people immediately and, after Pierleoni's deposition, soon became the intellectual leader of the Commune, calling for freedoms and democratic rights.

Because he remained a hero to large sections of the Roman people and the minor clergy, his ashes were cast into the Tiber, to prevent his burial place becoming venerated as the shrine of a martyr.

[11] Arnold rejected the power of the Roman church and believed that sinful clergy lost their right of administering the sacraments.