I bought "Truth and Tolerance Christian Belief and World Religions," because I thought that since it was written by Cardinal Ratzinger, who is Prefect of the Congregation for the Doctrine of Faith in Rome, that it would be an articulation of the Catholic Church's position in regards to the relevancy of other religions for helping people along the path of salvation. If that is what you are looking for, don't buy this book, because it does not focus on this type of doctrine and will not help you. Franicis Sullivan's book "Salvation Outside the Church," is probably still the best book on that subject, even though it is mor than ten years old and many papers have been presented by the Vatican since its publication. This book instead explores the role of what an individual's concept of truth should play in society.
By "truth," Ratzinger refers to the values that an individual holds as reference when making decisions. He states that "heaven begins on Earth." And he does not confine the people who are able to realize "truth" to Christians, nor even only believers in any sort of Divinity; agnostics and atheists are capable of this discernment to a degree too.
Being Christian, he believes that Christianity embodies truth in the fullest sense; that God is love and we are all called to know God as love and to spread His love. But he admits that no approach is perfect, since only God is capable of perfect knowledge of truth and love, and people are unable to understand God perfeclty. He concedes that Christianity has been susceptible to "diseases" in the past, such as the mentality that allowed to Crusaders to shed so much blood in Jerusalem.
The book is not an easy read. It is very philosophical and written in a style that is a cross between a philosophical text book and legal writing. The first section of the book briefly outlines and seeks to categorize different approaches of faith. The majority of the essays are from lectures that he has given, and the thoughts are not outlined as clearly as they are in most works presented as papers.
First, he outlines three ways of moving beyond myths, which have been observed in human history as schools of faith: mysticism, monotheistic revolution, and enlightenment.
Monotheism is further divided into three models: spiritual monism of India, universal Christianity, and Islam. I am not quite sure why or if he decided that Islam's approach is separate from Judaism, in the model. Judaism's place is not well articulated. Islam is introduced as having a different concept than universal Christianity because Islam believes itself to be the final revelation "beyond Judaism and Christianity;" and that there is one God. But Christianity believes in a Trinity. According to this logic, I would think Judaism would be closer to Islam. Perhaps, it is the finiteness of the plan that leaves Islam unto itself. The model is not mentioned again, ad this was the biggest lack of clarity I found in the book. It did not impact my comprehension of the rest of the book, because the book is a collection of related topics, rather than a study based on incrementally important chapters.
Next, he discusses a little bit about approaches universal Christianity used as frameworks for validating (or invalidating) the elements of truth that are inherent in religions. These include: inclusivist, exclusivist, and pluralism approaches.
He spends much time defining the terms he talks about, which makes the book dry, but for the persevering reader, deeper insight is introduced for concepts such as truth, democracy, freedom, and responsibility; words that have become over used and empty by society at large, in the second part of the book.
An individual or society's collection of religious beliefs are referenced in the word "truth." He posits that people who have more freedom, have more responsibility to make decisions with reference to truth in their life, in order to make the world a better place. He does not believe that it is possible to create a utopia, but that we actively seek to make the world better in relative to its current state.
The book occasionally mentions Christian teaching, but not any more often than it pulls from examples of Buddhism, Judaism, Islam, Hinduism, as well as from philosphers such as Platao, Socrates, Aristotle, Hegel, Kant, Marx, and many others. He empasizes the importance of not only reading "empty philosphy," but to study the issues that matter in life: such as concepts of truth that explore the meaning of life and that help us to better discern the consequences of our decisons. Rather than promote any one perspective of values, Ratzinger uses the book to exhort the reader to acknowledge whatever values s/he has that are true and to implement them in society to improve the world, with as much freedom as our lives give us the ability to do.