Most spurious words later added to the Bible probably entered the text accidentally, via something called ‘interpolation.’ What’s that?
In ancient times, scrolls were expensive. Some people made their own hand-written copies of important passages, but generally people didn’t own their own Bible. The entire community would own a copy to be shared by everyone. That copy would be read aloud for others to hear at their meetings.
Teachers used these working copies to preach sermons, and would add notes in the margins, or even in between the lines. Later, when the scrolls came to be copied for use by other churches (or just because the scroll was old and worn-out), scribes would not know whether the note was part of the original text or not.
It’s likely that the scribes copied the note into the main text to be cautious. After all, they don’t know if they are original words or not. Perhaps the scribe who made the first scroll had forgotten to put those words in, and they were scribbled in later by someone else as a correction? The scribe simply couldn’t know. So, he chose to play it safe and copy the words into the new scroll. After all, the words reflected what the community believed, so the scribe wouldn’t disagree with what they said.
The result is that many little notes and extra words entered the Bible text. Thankfully, we can compare manuscripts and use critical thinking to identify and cross out many of these (listed on this page).
Therefore, the popular belief that the Bible is a game of ‘Telephone’ which gradually changed its message over time is completely wrong. We likely have the original Bible text; our problem is quite different – extra words and phrases crept in, and we have to rip them out.