His religious policies, and his marriage to a Roman Catholic, made him mistrusted by Reformed groups such as the English Puritans and Scottish Covenanters, who thought his views were too Catholic. He supported "high church" Anglican ecclesiastics, and failed to help Protestant forces enough in the Thirty Years' War. His attempts to force the Church of Scotland to adopt high Anglican practices strengthened the position of the English and Scottish parliaments and were a cause of his downfall.