The Protestant leader's statements were communicated to ZENIT by Sigrid Spath, a German Lutheran, who at times has been Cardinal Ratzinger's interpreter and who, for more than 30 years, has worked in the general curia of the Society of Jesus and collaborates with the Holy See.
Spath revealed details of the public meeting she witnessed between the then prefect of the Congregation for the Doctrine of the Faith, and Wolfgang Huber, former Lutheran Evangelical Bishop of Berlin and now president of the Council of the Evangelical Church in Germany.
During the debate on the encyclical "Fides et Ratio," which took place in Rome in October 1998, Cardinal Ratzinger revealed that before entering university he had already read all of Luther's works written before the Reformation.
"That is, the reflections of Catholic Luther," Spath told ZENIT.
"Ratzinger invited those present to read those writings again, as they express the great battle that Luther had with himself to live and accept the teachings of the just and good God," she added. "'Dear Protestant friends, rediscover the Luther of those years,'" recommended Cardinal Ratzinger at the time.
"The debate lasted several hours," she recalled. "Bishop Huber was impressed by the intervention of the prefect of the Congregation for the Doctrine of the Faith and commented that Ratzinger is one of the few who really know Luther."
Cardinal Ratzinger's knowledge of Luther made possible the historic signing of the Joint Declaration on the Doctrine of Justification, approved by the Catholic Church and the World Lutheran Federation.
Some points of the proposal for the declaration presented in 1998 were rejected both by the Holy See as well as the federation.
When it seemed that the project would fail, the difficulties were surmounted by Bishop Johannes Hanselmann, former president of the World Lutheran Federation, and Cardinal Ratzinger, thanks to their long-standing friendship, which made possible a private meeting between them in November 1998.
After Dr. Hanselmann's death on Oct. 2, 1999, Cardinal Ratzinger revealed in a public address: "We had a very important meeting in my brother's house, in Germany, as it seemed that the consensus on the Doctrine of Justification had failed. In this way, in the course of a debate that lasted a whole day, we found the formulas that have clarified the points that still present difficulties. …
"With the formula elaborated in those days, both by the Lutheran Federation as well as the Catholic magisterium, they have been able to acknowledge that a consensus has been reached on some fundamental points of the Doctrine of Justification. It is not a global agreement, but with this formula it is possible to proceed to the signing of a document of consensus in the basic contents."