Final answer:
Charles I's enforcement of Arminianism caused instability by alienating Puritans and contributing to religious and political divisions, along with fiscal chaos, leading to a weakened England internally and externally.
Step-by-step explanation:
The policy of enforcing Arminianism by Charles I contributed significantly to instability during his reign. This approach alienated a substantial proportion of his subjects, especially the Puritans, who viewed the introduction of Catholic liturgy and theology into the Church of England as an existential threat to their religious beliefs. Furthermore, by marrying a Catholic princess and allowing the Archbishop of Canterbury, William Laud, to introduce controversial religious practices, Charles deepened the sectarian divide. His fiscal policies, which included imposing taxes not used for centuries, exacerbated the situation and led to fiscal chaos.
Charles' failure to work with Parliament, a body that could have offered representational governance and balance, also led to severe political instability. This situation was aggravated when details of Charles' secret Treaty of Dover, which vowed England's support of France in exchange for funds and a promise to relax anti-Catholic laws, leaked, causing widespread anti-Catholic and anti-Charles sentiment. All of these factors combined made England a country that was weak abroad, severely divided at home, and facing fiscal challenges – a legacy that Charles's brother James would inherit, further complicating England's political landscape.