How do I convince him to use a condom when he says we don't need one?

I'm 14. There is this guy I knew for a couple of years now. We are very good, close friends. As the months went by, we started to get sexually attracted to each other. About 2-3 weeks ago we had oral sex (I sucked his penis only). Now we want to do even more. We both want to actually have sex. I'm really attracted to him sexually....