German President Frank-Walter Steinmeier paid tribute to Benedict XVI, calling the late German-born pope a mediator between religions.

The unity of Christianity and the dialogue of religions, the coexistence of religion and society were especially close to his heart. He sought dialogue with Jews and Muslims, as well as with all Christian denominations around the world, Steinmeier wrote.

His work as Professor Joseph Ratzinger, Benedict's birth name, made theological and philosophical education more accessible, Steinmeier said. This allowed many people, "not only Catholics," he wrote, to find "a clear orientation" in his work.

Steinmeier said the late pope faced the depressing problem of worldwide sexual abuse and its systematic cover-up throughout his career, adding: "Here he was particularly responsible. Benedict knew about the great suffering of the victims and the enormous damage to the credibility of the church".

Benedict decided to resign at a time when he was sure he could no longer carry out his duties with the necessary strength, Steinmeier wrote, calling his resignation "an unexpected caesura in the history of the church."