Comma Johanneum and Erasmus (Cambridge History)

"In the case of the New Testament Erasmus shocked contemporaries by omitting the famous proof text for the Trinity in 1 John 5:7 where the genuine text reads: 'There are three that witness, the Spirit, the water, and the blood, and these three are one.' The spurious addition amplifies thus, 'There are three that witness on earth, the Spirit, the water, and the blood, and these three are one in Christ Jesus, and there are three that give testimony in heaven, the Father, the Word, and the Spirit'. Erasmus could not find this form in any Greek manuscript, and therefore omitted it. Such was the outcry that he rashly promised to insert the reference to the heavenly witnesses could it be found in any Greek manuscript. One was discovered at Dublin, late and worthless. Erasmus, having sworn to deliver the head of John the Baptist, made the insertion in his second edition in 1519. Happily Luther in his translation did not follow him at this point. But others did, including the King James Version. As late as 1897 the Sacred Congregation of the Holy Office, with the endorsement of Pope Leo XIII, declared the passage to be authentic. Forty years later this decision was reversed." (Cambridge History of the Bible. Cambridge: Cambridge University Press, 1963. Volume 3:10-11.)

Picture Attribution: Workshop of Lucas Cranach the Elder [Public domain], via Wikimedia Commons

See http://commons.wikimedia.org/wiki/File:Werkstatt_von_Lucas_Cranach_d.%C3%84._-_Portr%C3%A4t_des_Erasmus_von_Rotterdam.jpg