I hope this isn’t a silly question. Is it okay to highlight or underline texts in a Bible? I never used to write in any book, but recently I have found it helpful for me to underline texts and outline areas of texts I find important, so I can locate them quickly for future reference. Recently, I have wanted to do this in my Bible, but I don’t know if this is permissible.
Yes, it is okay to mark your Bible in such a manner to enhance your ability to study it. The purpose is not to deface the Bible but to use it more effectively. Of course, as a matter of prudential judgment, it might be best not to do this to a Bible that is meant to last for generations (such as a family Bible); but there is nothing wrong in principle with noting one’s own commentary and highlights on the pages of his study Bible.