Platon was born Porphyry Theodorovich Rozhdestvensky on February 23, 1866, the son of a parish priest in the Kursk Eparchy of Russia. He attended the Kursk Theological Seminary and married. He was ordained to the priesthood in 1887 and was assigned as a village priest in Lukashevsky. His wife soon gave birth to a daughter, but within five years he became a widower.