Planck was a devoted and persistent adherent of Christianity from early life to death, but he was very tolerant towards alternative views and religions, and so was discontented with the Nazi church organizations' demands for unquestioning belief.
The God in which Planck believed was an almighty, all-knowing, benevolent but unintelligible God that permeated everything, manifest through symbols, including physical laws. His view may have been motivated by an opposition like Einstein's and Schrödinger's against the positivist view. Planck was interested in truth and a Universe beyond observation, and objected to atheism as an obsession with symbols.
Planck regarded the scientist as a man of imagination and faith, "faith" interpreted as being similar to "having a working hypothesis". For example the causality principle isn't true or false, it is an act of faith. Thereby Planck may have indicated a view that points toward Imre Lakatos' research programs process descriptions, where falsification is mostly tolerable, in faith of its future removal.