not believing in Trinity
Yes, historically, denying the Trinity was punishable by death in several jurisdictions, particularly during the medieval and early modern periods in Europe and colonial America.
Europe: In 17th-century England, laws such as the 1648 Ordinance and the 1698 Blasphemy Act made the denial of the Trinity a capital offense; notable executions included Michael Servetus (burned at the stake in Geneva in 1553) and Thomas Aikenhead (hanged in Scotland in 1697).
Colonial America: The Maryland Toleration Act of 1649 granted freedom of worship to Trinitarians but explicitly sentenced those who denied the divinity of Jesus or the Trinity to death.
Religious Doctrine: The Athanasian Creed, influential in the Middle Ages and maintained by Roman Catholic and Protestant traditions, states that anyone who does not believe in the Trinity whole and unbroken will "doubtless perish eternally," a theological stance that historically justified civil persecution.
https://en.wikipedia.org/wiki/Michael_Servetus
