Planck, Max - And the Ultimate Intelligence
Type of Spiritual Experience
Planck regarded the scientist as a man of imagination and faith, "faith" interpreted as "having a working hypothesis" - in effect scientists work via belief systems.
He had little time, however, for religions’ definition of God. Six months before his death, someone [in the Catholic church] started a rumour started that Planck had converted to Catholicism, but when questioned what had brought him to make this step, he declared that, although he had always been deeply spiritual, he did not believe "in a personal God, let alone a Christian God."
The following quote shows that he was in essence a believer in an evolving God, a God that was increasing in power and function and that the Ultimate Intelligence would only ever be the Ultimate Intelligence when creation was 'complete'.
A description of the experience
Religion and Natural Science (Lecture Given 1937) Scientific Autobiography and Other Papers, trans. F. Gaynor (New York, 1949), pp. 184
Both Religion and science require a belief in God. For believers, God is in the beginning, and for physicists He is at the end of all considerations… To the former He is the foundation, to the latter, the crown of the edifice of every generalized world view.