Why was Luther summoned to the Diet of Worms?

Martin Luther was summoned to the Diet of Worms in 1521 primarily to respond to charges of heresy due to his writings, particularly his Ninety-Five Theses, which criticized the Catholic Church's practices, including the sale of indulgences. The Holy Roman Emperor Charles V sought to address the growing Protestant Reformation and maintain religious unity within his empire. Luther was asked to recant his views, but he famously refused, asserting his commitment to his beliefs based on scripture. This defiance marked a pivotal moment in the Reformation and solidified his role as a key figure in challenging the Catholic Church's authority.