I messed around with my sister tonight, I know what I did was very very wrong, and I don't know if I injected sperm into her. I kept drying it, and when I put it in her I almost right away took it out. I felt my dick and it had sperm on it, but I don't know if I can make her pregnant with just a little bit. If someone can tell me, I would appreciate that. If someone where to pray over me and my sister, we need the help because I'm too young to have kids, and it's my sister. I am currently asking God for forgiveness, and I know I am forgiven because God died on the cross and forgave us. Please get back to me as soon as possible.
Every act of sex carries the risk of pregnancy. Even if you didn't ejaculate, the pre-ejaculate fluid that drips from your penis can carry some sperm. All it takes is one sperm reaching a woman's egg cell to cause pregnancy. You won't know until your sister has her next period. If she has her normal blood flow, then she did not become pregnant.
But there is more wrong here than just a risk of pregnancy. You were engaged in an act of sex when you are not married. In the Bible that is called fornication. "Or do you not know that the unrighteous will not inherit the kingdom of God? Do not be deceived; neither fornicators, nor idolaters, nor adulterers, nor effeminate, nor homosexuals, nor thieves, nor the covetous, nor drunkards, nor revilers, nor swindlers, will inherit the kingdom of God" (I Corinthians 6:9-10). Since you had your penis in your sister, that act of fornication is also called incest. What makes incest a particularly abhorrent sin is because children born to parents who are close relatives tend to have a very high number of birth defects. Therefore, it isn't just a crime committed by the two of you, but it is also a sin against the child born who must live with the defects. It is so bad that in most places it is a crime that can land you in jail.
Often people focus on the final sin and forget that there were other sins involved as well. Your sin didn't start with you putting your penis in your sister. Prior to that, you committed other sins:
- Lust: A strong desire something that is wrong (Matthew 5:28; Mark 7:21-23).
- Sexual touching: Both touching through clothing and under clothing (I Corinthians 7:1).
- Lewd behavior: All the messing around that got you wildly sexually aroused (Romans 13:13-14).
- Nakedness: Exposing your private areas to another person.
When you understand the end point of a series of actions is sinful, then the actions that led you to that end point are also wrong. Even if this scare passes, you and your sister both need to make some radical changes in your lives so that nothing like this happens again.