Although the original texts of the Bible were inspired by God and are without error, the same cannot be said for later copies of the texts or translations made from them. Translators are human, and many have allowed their own religious biases to influence their work. Usually such mistranslations are relatively minor, but in some cases they are major blunders and promote erroneous teachings and doctrines.
One such blatant error, made by translators of the King James Version, is found in Acts 12:4, where the word Easter is used. In the original Greek, this word is pascha and refers to Passover, not Easter. Passover is a biblical festival mentioned in Exodus 12:11, Leviticus 23:5, Matthew 26:2, Matthew 26:17 and elsewhere in the Scriptures. In the New Testament pascha is used 18 times and is translated correctly in the King James Bible as "Passover," except in Acts 12:4, where the error was made. The New King James Version, and virtually all other translations, correct this mistake.
Another serious mistake in the King James and New King James versions is in 1 John 5:7-8. The latter part of verse 7 and first part of verse 8 did not appear in the Greek texts for the first 1,000 years after the Scriptures were completed. Around the year 500 this portion appeared in the Latin version known as the Vulgate. Apparently the insertion was an attempt to bolster the then-controversial belief in the Trinity. The words added are as follows: "in heaven: the Father, the Word, and the Holy Spirit; and these three are one. And there are three that bear witness on earth."
None of the Greek manuscripts of the New Testament up to the year 1300 contain these words. "The textual evidence is all against 1 John 5:7. Of all the Greek manuscripts, there are only two which contain it. These two manuscripts are of very late dates, one from the fourteenth or fifteenth century and the other from the sixteenth century. Both clearly show this verse to be translated from the Latin" (Neil Lightfoot, How We Got the Bible, 1963, pp. 57-58).
Apparently monks who copied the Greek New Testament text in the 14th or 15th century added this verse from the Vulgate. Even the Catholic Jerusalem Bible admits this verse is not authentic and has left it out. Notes in the Jerusalem Bible explain that this was a marginal note in one of the copies of the Vulgate that was added to the late Greek manuscripts already mentioned.
The verse from 1 John 5:7 should read, as hundreds of the oldest Greek texts and most modern translations read: "In fact there are three witnesses, the Spirit, the water, and the blood; and these three are in agreement" (Revised English Bible). This refers to the witness of Jesus Christ being the Son of God (1 John 5:5).