Candidius was born in 1597 at Kirchardt in the Palatinate. He studied at Leiden in the Dutch Republic from 1621 to 1623, when he was persuaded by Sebastiaen Dankaerts to minister overseas. Before arriving in Formosa in 1627 Candidius worked in Ternate, Moluccas. Having arrived in Taiwan he refused to live in the Dutch castle Zeelandia and settled in the native village of Sinckan (modern-day Sinshih) instead.
In 1632 he married Saartje Specx, daughter of Governor-General Jacques Specx. Specx had previously evoked a scandal in Batavia and Holland when she was discovered making love to a young soldier in the private quarters of Specx's predecessor, Jan Pieterszoon Coen, who was known for his harsh discipline. Narrowly escaping a death sentence, she was flogged and her lover beheaded.
After a year in residence in the region of Tayouan (present-day Tainan), Candidius commented regarding his missionary duties that:
"I have used great diligence to learn their language, and from the outset to instruct them in the Christian faith; and I have succeeded so far that a fortnight before Christmas of the year 1628 there were a hundred and twenty-eight persons who knew the prayers and were able to answer in the most satisfactory manner with regard to the principal articles of our Christian faith; but for certain reasons none of these have been baptized."
Candidius returned to the Netherlands in 1639 and went to Batavia (Jakarta) in the Dutch East Indies (Indonesia) in 1643. There, he served as rector of the Latin school until his death on 30 April 1647.
Sun-Moon Lake in central Taiwan was named Lake Candidius in his honour and is referred to thus in older English writings, although this name was not adopted by the local inhabitants and later fell into disuse.
- Georgius Candidus. Discours ende Cort verhaal, van't Eylant Formosa, ondersocht ende beschreven, door den Eerwaardingen (A Short Account of the Island of Formosa in the Indies) (in Dutch).
- Donald Frederick Lach & Edwin J. Van Kley (1993). Asia in the Making of Europe. University of Chicago Press. p. 277. ISBN 9780226467535. OCLC 221772798.
- Gerald H. Anderson (1998). Biographical Dictionary of Christian Missions. New York: Macmillan Reference. p. 113. ISBN 9780028646046. OCLC 36017191.
- Specx, Sara (1616/1617-ca. 1636)
- Campbell, Formosa under the Dutch, Introduction, p. viii.
- Campbell, Sketches, p. 336.
- Candidius, G. (1903). "Account of the Inhabitants". In Campbell, William (ed.). Formosa under the Dutch: described from contemporary records, with explanatory notes and a bibliography of the island. London: Kegan Paul. p. 25. OCLC 644323041.
- Campbell, William (1915). Sketches of Formosa. London: Marshall Brothers. OL 7051071M.