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Why did Thomas More disagree with Henry VIII about his marriage to Catherine of Aragon?

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Portrait of Sir Thomas More by Hans Holbein the Younger, showing More in dark robes and a black hat, wearing a gold chain of office, seated against a green and yellow draped background. — Thomas More *Sir Thomas More*, oil on panel by Hans Holbein the Younger, 1527; in the Frick Collection, New York City.

Thomas More’s disagreement with King Henry VIII regarding his marriage to Catherine of Aragon stemmed from a fundamental conflict between his conscience and the King’s political objectives.

In 1527, Henry VIII sought an annulment of his marriage to Catherine, arguing that the union was void and even incestuous because Catherine had previously been married to his late brother, Arthur. While Henry attempted to convince More of these biblical scruples, More conducted his own study of the matter and concluded that Catherine was, in fact, the King’s true wife.1

More’s opposition deepened as the King moved to break with the Catholic Church to secure the annulment. More refused to sign a letter pressuring the pope to declare the marriage void and later declined to attend the coronation of Anne Boleyn. Ultimately, More’s refusal to acknowledge the King as the supreme head of the Church of England or to validate the annulment through the Act of Succession led to his imprisonment and execution in 1535.5234