QuestionI am a Christian and I have been home schooled my entire life so I have never been in the public school where they have big locker rooms where guys see other guys' penises.
I don't know if looking at my penis is a sin or not. Every time I look at it, it will start to get big (erection). Is looking at my penis sin or lead to anything bad?
"And those members of the body which we think to be less honorable, on these we bestow greater honor; and our unpresentable parts have greater modesty, but our presentable parts have no need" (I Corinthians 12:23-24).
As we mature, we realize the significance of our genitals. A child might not give much thought to clothing. He mostly dresses for warmth or because his parents told him to do so. But when we reach puberty our innate sense of propriety becomes active and we naturally hide what we are embarrassed to think about.
There is nothing wrong with looking at your body. Most people do as they bathe and you can't help seeing yourself when you are using the restroom.
I don't think it is seeing your penis that is really bothering you. I think it is the sexual feelings that are coming awake inside your body that you find so disturbing. It is one thing to know that sex outside of marriage is wrong, but it is a different matter when you realize that your own body craves sex. A part of the difficulty comes because it is new. We aren't disturbed to find out that we get hungry or thirsty because those feelings have been with us for longer than we can remember. The desire for sex is just as much a part of your body, but it doesn't develop until you start developing. Thus the innocent matter of seeing your penis, which you have seen most of your life, now takes on new meaning and awakens desires that you are uncertain are proper.
First, understand that the desire for sex is normal. It is how God designed your body. It is how those desires are expressed that can be wrong. Satan uses your desires to tempt you into considering having sex outside of marriage. The desire for sex is neither right nor wrong, It is the lust for sex outside of marriage which is wrong (James 1:13-16).
The reason you are getting erections when you see your penis is because the ability to get erections is new and the sexual feelings in your body are also new. The erections and the feelings that come with it are called "arousal." Eventually you will get used to it. However, you will be going through a period where it will seem that your penis has a mind of its own and it will get erect many times a day, often for no apparent reason. As annoying as it is, it will eventually fade.
Seeing your penis is not a sin. Touching your penis is not a sin. Having erections or even ejaculations are not wrong, in and of themselves. They are how your body is supposed to work. However, using your penis to have sex with someone who is not your wife, or even strongly considering having sex outside of marriage though you don't actually do it, are both sins.
I know that you are curious at this stage about other guy's equipment. You want to know whether other guys have similar problems and how your development stacks up against other guys your age. While the curiosity is understandable, it really doesn't matter. Each guy develops at his own rate. Whether you are bigger or smaller than another guy doesn't change the fact that you are at the proper point for your development, nor does it make you more or less of a man.