I'm a 15 year old boy. I go to church, I'm a Christian, and I love church, but I wonder about stuff like my size in my private spot and stuff about puberty. I searched on Google. I guess since I'm going though puberty reading stuff like this makes me hard and I leak semen. Is that a sin? I feel bad, but I didn't really do anything wrong, did I? I'm not looking at bad pictures, masturbating, or anything like that, so I don't see why I get hard and leak. I just want to know if I'm doing anything wrong. I am saved and I love Jesus.
Technically you can't be saved without loving the Lord. "Blessed is a man who perseveres under trial; for once he has been approved, he will receive the crown of life which the Lord has promised to those who love Him" (James 1:12).
Your body does a large number of things at the same time. Much of it doesn't require any thought on your part, and a some things happen by conscious thought. For example, you move your arm by conscious thought. It doesn't wave around when it takes a mind to moving. Yet, if you touch something hot, your arm will jerk back before you even realize that what you were touching was hot. That jerk back motion is an automatic response. Even with some automatic responses, if you focus on it, you can override the response. Thus, you can dumbly keep touching something that is too hot despite your body's efforts to save you -- that is what allows people to rescue another from a burning car.
There are still other parts of your system that require no thought on your part. You don't need to tell your stomach to digest your food or your kidneys to filter out wastes from your blood. These organs run mostly on their own. They might respond to a thought. You might start reading about food and your stomach growls as the kicks into gear even though you haven't eaten a bite.
Your reproductive organs are also a mixture of conscience thought, semi-automated responses, and automatic responses. For example, erections are a semi-automatic response. Your body will produce an erection as soon as it detects an inkling that you might be having sex. When you are young, your body has no clue what that means so everything gives you an erection. As you get older it gets wiser and makes distinctions. Somewhere in your twenties you'll be able to keep an erection from happening if you focus on it.
Other organs are automatic. Your Cowpar's glands produce a clear, slick liquid that is called pre-ejaculate. In slang it is sometimes called pre-cum or pre-nut. It isn't semen. Semen is a thick milky-white to slightly yellow liquid that comes out with ejaculation and orgasm. Pre-ejaculate drips from the end of your penis when you get sexually aroused. Its purpose is to clear out your penis in preparation for ejaculation. While you can eventually stop an erection by focused thought, you can't turn off the Cowpar's glands in this way.
What is happening is that you are reading about things related to sex. Your brain is saying, "SEX!" and body is responding to the signal. Your penis inflates and becomes erect. Your Cowpar's glands begin pumping out droplets of pre-ejaculate fluid. Eventually, because nothing further happens, your body realizes it was a false alarm and your penis deflates. The Cowpar's glands stop, but because your erect penis is bigger than your flaccid penis, the remaining fluid comes out in a big splotch and the little that remains eventually drips out. You see it as a wet spot on your pants, which, depending on the amount, can be really embarrassing. Fortunately, pre-ejaculate fluid evaporates fairly quickly and doesn't leave a stain.
Therefore, you aren't doing anything wrong in what you describe. Your body is just working as it was designed to do. There is no reason to feel bad about it. It would be like feeling bad for needing to urinate or getting hungry.
Feel free to ask any other questions you might have.