I think I'm gay. How can I tell?
It is popular today to mix the ideas of attraction, temptation, and curiosity as if they equivalent to the actual deed. "Gay" is merely slang for being a homosexual; that is, a person who has sex with someone of the same gender. Homosexuality is the deed. It is when a man has sex with another man or a woman has sex with another woman. In the Old Testament, it was considered a sin that carried a death penalty. "If a man lies with a male as he lies with a woman, both of them have committed an abomination. They shall surely be put to death. Their blood shall be upon them" (Leviticus 20:13). In the New Testament it is also described as a sin. "For this reason God gave them up to vile passions. For even their women exchanged the natural use for what is against nature. Likewise also the men, leaving the natural use of the woman, burned in their lust for one another, men with men committing what is shameful, and receiving in themselves the penalty of their error which was due" (Romans 1:26-27). "Use" in this passage is a polite way of translating a Greek word for having sex.
In the Bible there is also a sin called "lust" which is to strongly desire to do something you know is wrong. In God's view, to strongly desire to do something is just as bad as actually doing it. They are two different kinds of sin, but they are both equally wrong. Therefore, a guy strongly wanting to have sex with a woman, even though they are not married is committing the sin of lust. "But I say to you that whoever looks at a woman to lust for her has already committed adultery with her in his heart" (Matthew 5:28). It is not just limited to adultery. You can lust for other sins. Thus for a man to strongly desire to have sex with another man is committing the sin of lust and that is just as bad as the actual act of homosexuality.
What often confuses young men is the fact that their bodies are easily aroused with a desire for sex. If something causes a young man's penis to go erect, he assumes it is because he desires to have sex with whatever caused the erection. The problem is that the body really doesn't know what sex is yet. It has a new feeling and new responses that it plays with trying to figure out when is the appropriate time for the feelings and responses to take place. The truth is that anyone -- male, female, or even the person himself -- can cause a male to orgasm and ejaculate. That is because for the male, sex is a physical act and the body has instinctive responses.
Thus, being a homosexual (or gay) is no different than someone being a fornicator or adulterer. Yes, your body responds to what it thinks is a sexual situation, but you always have a choice of whether to give in to instincts or refuse to do what is wrong. When your body gets aroused by a female, that doesn't make you a fornicator; neither are you a homosexual because your body got aroused when a male was around.
Another problem is that young teens enjoy teasing people. The more they are bothered by something, the more merciless the taunts. It is not unusual for young men to be called "gay" simply because a bunch of boys decided that some action or behavior is different from their own. Truth has nothing to do with the taunting -- they are only interested in making another person feel bad about themselves. Sadly, some people decide the taunting is true. A guy called "ugly," "fat," "weak," or "gay" sometimes falsely decides the taunts must be true and starts describing himself by those taunts. In your case, you have a male body. That body is designed to have sex with a female (your wife) one day. It is your choice who you marry and have sex with. You are not ruled by other people's opinions, by instinct, or by temptation.
The current fad in society is to claim that homosexuality isn't really a sin. It has always been the case that whatever sin a person is involved can't be that bad if the person likes doing it. So people have been coming up with all sorts of reasons to justify their sin. One claim is that a person is born homosexual. All sorts of experiments have been tried to prove this -- and every one has failed to prove the claim. Not that it matters to the supporters, even a hint leaning in the direction they want is claimed to be proof and though it is later disproved, that inconvenient truth is ignored. But the general population never thinks to question the evidence given, and so myths are born. Even though all you have to do is look at your body and know you were not designed to have sex with males, the doubts that what these other people claim could be right makes you and other young men question even plain facts.