Our pastor made some excellent points in 6 Reasons Why You Should Write In Your Bible. Go to the link for more details on each reason.
1) Marking up the Bible helps you see what’s there.
2) It’ll help you process what is there.
3) You’ll remember more of the Bible.
4) You can find what you found.
5) Create Your Own Cross-references.
6) Most importantly, it will help you worship God with your heart and mind.
Here’s my one reason not to: If your handwriting is so bad that it makes the Wing Dings font look legible and you can’t even read it yourself.
I wrote in my Bible once. I’m not sure why. This is from the Bible I got as a kid, which I never read. But for some reason this was written in the front. It will give you some keen insights into my spiritual condition at the time.
So I guess there is a 2nd reason not to write in your Bible: Don’t do it if you are going to write something stupid.
This is what I’ve been trying to tell people my entire life.
Whether you write in your Bible or not, just be sure to read it. A lot.