Final answer:
St. Thomas Aquinas, an Italian Catholic medieval Doctor of the Church, utilized Aristotelian philosophy and asserted that moral law is a part of God's divine plan. Known as Doctor Angelicus, his work greatly influenced European philosophy and integrated Aristotelian concepts into Christian theology.
Step-by-step explanation:
The Italian Catholic medieval Doctor of the Church who extensively utilized Aristotelian philosophy and maintained that moral law was part of God's divine plan for the universe was St. Thomas Aquinas (1225-1274). He was a notable theologian, Aristotelian scholar, and philosopher, often referred to as the Doctor Angelicus or the Angelic Doctor. Aquinas is widely recognized for integrating the ideas of Aristotle into Christian theology, and his works had a significant impact on the direction of European philosophical thought for many generations. His synthesis of Christian doctrine with Aristotelian philosophy highlights his belief in a rational, ordered universe with a moral law created by God.
Aquinas is best known for his 'Five Ways' to demonstrate the existence of God, and his work influenced both religious and philosophical discussions, establishing the foundation for Scholasticism. Additionally, he brought new perspectives to the conversation by introducing the work of Jewish and Islamic philosophers to medieval Christian thought, further invigorating Scholastic philosophy. It is through this fusion of thoughts that Aquinas played a critical role in integrating and advancing Aristotelian philosophy within the framework of Christian theology.