I want to tell my boyfriend of 4 months that I am not ready for sex as I'm only 15 and he's 19. Also, that I love him more then sex, and if he wants to leave because I don't want sex now he can because I know he's not the guy for me. If he truly loves me he would wait till I'm ready and not give me excuses.

How can I tell this to him? Thanks

Say, "I really care for you, but at 15, I'm not ready to go that far. I'm not ready for the consequences that can result in sex. I hope you understand."

If all else fails, tell him that you don't want him to go to jail, because in most states a sexual relationship between two people your age is illegal.

Simple if he makes sexual advances tell him no if he doesn't stop leave

I think you that you tell him exactly what you told us. If he can't handle it or says, that having sex will show him how much you love him then you need to move on.
You want a man that puts you first, cherishes you and listens to your needs. If he doesn't do that now, he most likely will not later in your relationship.

Good for you, it's so nice to hear of a 15 year old that knows what she wants and sticks to it.

Don't sugar coat it. It lets him know that your serious. When it comes to guys you have to be very blunt about what your thinking for them to fully understand where your coming from. I think they way you just said it is fine.