Max Planck (1858-1947)
The well-known American historian of physics and astronomy, John.L. Heilbron (1934) wrote about the religious views of Max Planck in The dilemmas of an upright man: Max Planck and the fortunes of German science. (Harvard University Press 1986)
"On the scientist side, Marxist writers have lamented such flagrant bourgeois idealism in a man whom otherwise they admire as a self-taught materialist. On the other side, Church spokesmen could scarcely become enthusiastic about Plankc's deism, which omitted all reference to established religions and had no more doctrinal content than Einstein's Judaism.
It seemed useful therfore to paint the lily, to improve the lesson of Planck's life for the use of proselytizers and to associate the deanthropomorphizer of science with a believ in a traditional Godhead.
Six months before his death from stroke on 4 October 1947, a rumour started that Planck had converted to Catholicism. An engineer applied to him for the reason that had brought him to such a step.
The reply was not useful to missionaries.
He had always been deeply religious, Planck said, but he did not believe "in a personal God, let alone a Christian God. A God without qualities, a religion without trappings, life without compartments, knowledge without divisions - in brief, a worldview without extremes - have little appeal to prophets and promoters."