The Summa Theologica (orig. Summa Theologiae) was written by St. Thomas Aquinas in the 13th century. It is the magnum opus of St. Thomas' body of work and is still regarded as one of the most precise, detailed collections of Christian theology. It's contents are famous for being extremely nuanced and well-argued and the work still retains a high level of respect and authority in the Catholic and Christian religions today. The book in any unabridged format comprises thousands of pages and many sections and countless sub-sections and is one of the most comprehensive arguments ever comprised in Western history.
St. Thomas' Summa contains broad, theological arguments such as the existence of God, the qualities of God, and God's goodness in spite of the existence of evil. It also contains insightful arguments about the roles of faith and reason, describing at length how one balances his love for God with his desire to be philosophical and open-minded. The work includes detailed arguments within Christian theology about predestination and fatalism, as well as answering philosophical question about existence and time and their relationship to God, questions which are still alive and thriving in Christian philosophy today.
Written in the style of question-response, Aquinas is careful to position his arguments beside any other formidable arguments on any given topic. This means that when he talks about reason and knowledge, for instance, he will refer to arguments from Aristotle, Averroes, Augistine, Anselm and many more. The work is holistic in that it makes such an effort to include counterpositions to his own arguments, and where no one has written contrastive arguments, he himself supplements the article with his own thoughts some positions different than his own held position. But then, of course, he is thorough in arguing his held position efficiently in spite of different arguments offered.
St. Thomas was regarded in his day as a very studious, devout man. He was a deep thinker as is evident in the Summa Theologica and his writings continue to be of aid to the philosophical minds and religious minds alike as they have been for hundreds of years. Though his arguments are Christian in their religious orientation, the work is palatable to people of any faith and many will find it to be insightful and inspiring regardless of their predispositions.