Why did Parliament choose to execute Charles Stuart?

A resistance force led by Oliver Cromwell opposed King Charles I, partly because he was Roman Catholic and they disapproved of the power he had given to the Catholic Church. In addition, he led a wasteful, decadent lifestyle at a time when many Britons starved. In addition, He was a Stuart, and many Cromwell supporters believed that the Stuarts had not come to the throne legitimately. The result of Cromwell's uprising was an English civil war between the Roundheads, a Protestant group led by Cromwell, and the Cavaliers, led by the king. When the Cavaliers were finally defeated, Cromwell gained supreme power over the government and was called the Lord Protector. He was a cruel, ineffective leader. His government condemned the king for treason, and the king was executed.