How did Thomism influence Christian ideas about moral excellence and happiness?

Thomism, the philosophical and theological system of St. Thomas Aquinas, profoundly influenced Christian thought by integrating Aristotelian ethics with Christian doctrine.12

Moral Excellence

Aquinas adopted the Aristotelian view that moral excellence is a cultivated state of character, expressed through actions that avoid both excess and deficiency. He maintained that morality is derived from human nature and activities objectively suited to it, rather than being determined by the arbitrary will of God. By linking virtue to human flourishing, Aquinas argued that doing what is right is inherently aligned with one's true good. He further expanded the traditional cardinal virtues—prudence, temperance, fortitude, and justice—by incorporating the three theological virtues: faith, hope, and charity.342

Happiness

While Aquinas agreed with Aristotle that all human action is directed toward an ultimate end or summum bonum connected to happiness, he provided a distinctively Christian transformation of this goal. He argued that true happiness is not found in philosophical contemplation or political virtue alone, but in the beatific vision—the ultimate love and knowledge of God. While limited happiness can be experienced on earth through a life of virtue, the perfect fulfillment of human happiness is a reward of heaven, granted by God’s grace.12