Reason #19: They are trying to read a Bible they cannot read.
I grew up reading the King James Version. Many of the verses I quote I quote from the King James Version. For the first ten years of pastoral ministry, I gladly preached from the King James Version. I think the beauty and flow of the King James Bible is beyond compare. Why mentioned all that here? How could reading the King James Bible or an older translation be a problem with assurance? To be free we need truth and we need to know truth. To know truth we need to understand truth.
The truth is, we do not talk in King James English. People may pray in King James English, but it is not their heart language. The English language has changed a lot since 1611. We do not talk like that or use words in the same way they used them in 1611. Let me know if you need some actual examples.
If I have offended you in this reason, allow me to add this. I would be willing to guess that many people who carry a King James Bible are not reading from the original translation. Rather, they are reading from a modernized version. I have a copy of the original 1611. Your church might have a copy somewhere. It may even be under lock and key. The truth of the matter is, hardly anyone actually reads from a 1611 version and many people would find it very difficult to read from the original 1611 KJV Bible. Rather, they are reading from a more current English translation. Here is a copy of John 3:16 and a few surrounding verses in 1611 KJV.
My point here is, read and study from a translation (not a paraphrase) of the Bible you can read, follow, and understand. I read and study from several translations; primarily the NKJV. I have found it maintains the flow of the KJV. It replaces some of the words we no longer use with ones we do use. In addition, it does not make changes just for the sake of change. Some Bibles I have read leave me wondering if they changed some words just because they wanted it to be different from the KJV, not because it made the translation better to read.
Probably the most literal English translation is the NASB. When I was in seminary for my first seminary degree, the professors held it in high regard for its accuracy in translating from the original languages to the English language. All I am saying here is, read and study from a translation you can read. If you need or want some further help in this area, let me know.