The best thing to do is sit them down and talk openly with them. Let them know where your heart is and how you truly feel. You may not want to start the conversation right off with "I'M GAY!" You need to let them know that their ideals of you is not what they may have painted in their heads. Your parents will always love you unconditionally, but that doesn't mean they will accept the life you have chosen for yourself. If they do choose to turn a blind eye to your lifestyle...know that they are turning from what is a sin in their eyes. Whatever happens, love your parents through it all...they are the only ones who will be there for you when the "stuff" hit the fan! I hope everything works out for you!

I’m concerned about your safety and therefore would highly suggest that someone else be present besides your boyfriend when you tell your parents.

My parents didn’t take so well when I told them but they slowly came around although, the topic of my girlfriend or lifestyle is off limits (Don’t ask/don’t tell.)

I would start the conversation off with mom/dad I need to talk to you and then follow with the I’m gay or the fact that you are gay, explain to them that you understand they do not approve but you will not change your ways etc etc in a responsible manner.

If your parents take it out of line request a foster home or find another place to sleep for abit (Allowing them to cool off)so that it can sink in.
Just some suggestions…

I know this is going to sound horrible but don't tell them. I'm sure your parents have a lot of wonderful traits outside of their homophobia and if nothing else they are the shelter that you will grow under until you're an adult yourself. Putting yourself in a possible my-way-or-the-highway position only makes you sacrifice something you need one way or the other. At 13 you are a child in their eyes. They almost certainly won't take your sexuality seriously until they can see you as a sexual entity, which depending on their religious fanaticism could be well into your 20's. Also at 13 if your parent's can't deal reasonably with your sexual preference you're taking on hardships that are infinitely worse than spending a few years in their closet.

I'd say don't come out to your parents but do stand up for homosexuals. Don't let their intolerant views go unchallenged whether they're focussed at Homosexuals, racial minorities or any minority group. Think of it as your responsibility as the open-minded one in your family. When you are in a position to tell your parents about who you are inside it will make your stance stronger if you have consistently defended others like you.

Wait till you are of legal age. I told mine at 16 and they kicked me out and it lead to bad things...so I say wait till you are established and threw with school,etc..
Good luck.

Or at least have a place of your own! If you really have to tell them though make sure someone else is there with you, counsellor, friend or what not, trust me you will need the support.