There are primarily six passages in the Bible that concern the issue of homosexuality. In Leviticus 18.22 it says that it is an abomination for a man to lie with another man as with a woman. In Lev. 20.13 the death penalty is prescribed in Israel for such an act, along with adultery, incest, and bestiality. In Gen. 19 Sodom is destroyed for their homosexuality and wickedness.
In I Cor. 6.9-10 Paul writes, “Do you not know that the unrighteous will not inherit the Kingdom of God? Do not be deceived; neither the sexually immoral, nor idolaters, nor adulterers, nor men who practice homosexuality, nor thieves, nor the greedy, nor drunkards, nor revilers, nor swindlers will inherit the Kingdom of God.” The words in the list translated “men who practice homosexuality” refer in Greek literature to the passive and the active partners in male homosexual intercourse. In I Tim. 1.10 along with fornicators, slave traders, liars, and murderers as “contrary to the sound teaching of the Gospel.” In Rom. 1.24-28 Paul states,
Therefore God gave them up in the lusts of their hearts to impurity, to the dishonoring of their bodies among themselves, because they exchanged the truth about God for a lie and worshipped and served the creature rather than the Creator, who is blessed forever! Amen.
For this reason God gave them up to dishonorable passions. For their women exchanged natural relations for those that are contrary to nature; and the men likewise gave up natural relations with women and were consumed with passion for one another, men committing shameless acts with men and receiving in themselves the due penalty for their error.
These are all commandments against homosexuality. However, I think the strongest passage concerning sexual practice is Jesus’ commands concerning marriage. Mark 10.6-8 says,
“From the beginning of creation, God made them male and female. For this reason a man shall leave his father and mother and the two shall become one flesh. Consequently, they are no longer two, but one flesh.”
απο δε αρχης κτισεως αρσεν και θηλυ εποιησεν αυτους 7 ενεκεν τουτου καταλειψει ανθρωπος τον πατερα αυτου και την μητερα [και προσκολληθησεται προς την γυναικα αυτου] 8 και εσονται οι δυο εις σαρκα μιαν ωστε ουκετι εισιν δυο αλλα μια σαρξ
This is a positive command for man to be with woman. The whole narrative of the creation of man and woman [and marriage] in Genesis 1-2 depict God’s plan for marriage. For man and man to be one flesh would be contrary to God’s command. These are by no means exegeses of these passages. (For more on Old Testament law and how to understand it please see my exegesis of Lev. 19.26-28.) I think it’s quite clear the Bible teaches that homosexuality is a sin. One must distort the text and perform fallacious exegetical gymnastics to get around this.
The question/problem is raised when this becomes a genetic trait. If God allowed for the homosexual gene to pass to any one person how said person can be responsible for their own genetics? It’s like me being held in condemnation because I have blond hair and blue eyes. How is that my fault? I haven’t been following biology and chemistry as much as I should. I’ve been focusing on cosmology and physics. I hear both sides: there is a gay gene and there isn’t a gay gene. I would tend to believe that there is not a gay gene but I will not base my position on whether or not there is. It could be a byproduct of genetic variation and evolution. (Let’s be honest, I have no idea how anyone can say that homosexuality is evolutionarily advantageous… Think about it.) For the sake of continuation let’s assume that there is a gay gene.
Where does sin come from? It comes from our choices and Adam. Our relationship to Adam is by imputed sin since he was our federal head–the representative of humanity before God. (There’s also a doctrine of inherited sin. I haven’t seen a convincing model for how exactly inherited sin would function but that’s still a consideration.) The argument for non-liability because of genetic homosexuality is similar to the argument for genetic alcoholism. Sure, there are genetic predispositions to alcoholism. I think that’s pretty well established. However, you’re not born with vodka in your hand. It’s still one’s choice to drink. By that choice of consuming alcohol you activate those genes to incline your need. According to my understanding, it’s similar to the biochemical function of addiction. What starts addiction? The choice to start the first dose of the substance. Yes, children are unfortunately born addicted to heroin and other drugs due to the mothers’ constant use of the substance. In that situation the child is, of course, not responsible for the addiction. But this is different. This is a temporary effect of the drugs and over time the biochemical need for the substance will deplete. (Drugs and pharmaceuticals will certainly ease the transition.) So, to compare homosexuality to this would be fallacious. It’s a false analogy. If one wants to say that homosexuality is a season and depletes after abstaining from the practice then I don’t see how this is an argument against liability for the sin.
Is homosexuality like race? No. Let’s think about this. Can one abstain from being white? No. Can one abstain from practicing homosexuality? Yes. Can there be a predisposition to homosexuality? Sure. However, what sin are we not predisposed to committing? I believe one can be a Christian and have a homosexual orientation or attraction but I think the Bible is clear that it’s the practice of homosexuality (both mentally and physically). Can a Christian have an orientation towards anger, jealousy, greed, or pride? Sure. It’s the practice in the heart, mind, and body that is sin. For a good popular level paper on this please see William Lane Craig’s paper, “A Christian Perspective on Homosexuality.”
We did not choose to have imputed sin, but we have it. Is it Adam’s fault? Well, it’s your fault. You would have chosen to go contrary to God’s commands had you been in Adam’s place. If you deny that you’re exalting yourself. Think about it.
So, if homosexuality is genetic how can it be a sin? We’re all born sinners whether that’s by physical action, of the heart, or of the mind. We are held accountable for every means of sin and every means of sin breaks God’s law and are contrary to his holiness. I believe it’s a category error to argue that genetic predispositions towards sin are not actually sinful.