QuestionCan someone develop herpes by sucking his own penis? Can two people develop HIV by doing oral sex even though neither person has HIV?
Both herpes and HIV are diseases caused by viruses. In order to catch these diseases, you have to be in contact with someone who already has the disease. Therefore, you cannot catch a disease from yourself. If you don't have it, you can't give it to yourself. If two people don't have a particular disease, they can't pass what they don't have to another person.
However, the problem with most sexually transmitted diseases is that a person can have a disease and not be aware of it. Herpes shows up as a rash a few weeks after it is first caught. The rash then goes away even though the person still has the disease. It flares up periodically, but continues to appear to go away without treatment. A person with herpes can transmit that disease to another person most easily when the rash is present, but he can in some circumstances give the disease to another person when no rash is visible.
HIV doesn't give symptoms for years after a person contracts the disease, yet it can be passed on before symptoms appear.
The problem with having sex with someone you are not married to is that such people rarely stay with one partner. Because of exposure to a number of people, they often pick up a disease and will expose others to that disease, and only learn later that they were infectious. Another problem is that people lie to get what they want. A person may say they don't have a disease, but are they telling the truth? If they are willing to break God's law against having sex outside of marriage, what is to stop them from telling a lie just so they can have sex?
Anytime you have sex with another person outside of marriage you run the risk of catching a disease. It doesn't necessarily have to be a disease that we have no cure for, there are numerous diseases passed on through sexual acts. That is why the Bible warns that when a person engages in sex outside of marriage he runs a risk: "Whoever commits adultery with a woman lacks understanding; He who does so destroys his own soul. Wounds and dishonor he will get, And his reproach will not be wiped away" (Proverbs 6:32-33).