You can't just mention the word "sex" or "intercourse" to be X-rated, you have to describe it in detail. The Bible does not do that. It occasionally mentions "intercourse", and it mentions deaths and killings, but it does not describe any of these with any details at all.
There's no logical reason why it shouldn't be appropriate for people younger than 17. Stop trying to force your beliefs on other people and tell people what they can't read.