"I am a member of the evangelical church. I believe in God and religion is also my constant companion, and has been for the whole of my life," she said on a videoblog when answering questions from a theology student.
"We as Christians should above all not be afraid of standing up for our beliefs," she added.
The structure of the world relating to belief was a, "framework for my life that I consider very important," she said.
The Frankfurter Rundschau newspaper noted on Tuesday that until now Merkel had been very quiet on the subject, despite the much-cited fact that her father was a protestant pastor.
She was more intensely affected by her family home and the Christian faith than she was by her study of physics and scientific thinking, her biographer Volker Resing suggested to the paper.
"And now she has realised that her avowal of Christianity is important - as a signal within the secular society, but also to her party members who have often accused her of not being concerned with the C [in the party's initials CDU]," he said.
Just less than a year before the general election in Germany, is the chancellor fishing for votes from the declining Christian community, despite friction with the Pope and her liberal position on stem cell research, the Frankfurter Rundschau asked.
Such a suggestion has always been too low for Merkel, which is in part why she has always kept religious questions private, the paper said. But it also suggested that her comments were a reaction to the strong media presence of the Muslim community in Germany.