A common argument forwarded by pro-homosexuality Christians who seek to establish that the Bible (minimally) does not teach against homosexual marriage is what I have seen called the Orientation Argument. This argument on first glance seems to potentially hold some water, but as often is the case, simply rooting the passage being applied in its greater context reveals the misappropriation.
The argument goes something like this.
Although Paul, in places like Romans 1, argues against homosexuality by claiming it is unnatural, Paul could not have conceived of what we have identified as a homosexual orientation. For those with a homosexual orientation, it is natural for them to be attracted to members of the same gender, and behave accordingly. Thus, if Paul knew what we knew… he would say that it is contrary to nature for the homosexual to act toward other gendered individuals.
Now, ignoring the arrogance and utter lack of evidence that Paul would be aware of homosexual orientation. This argument simply doesn’t bear weight. It is true that Paul roots the argument in nature. However, the very existence of the desires (even if we grant that they are genetic and unavoidable) is itself seen by Paul as a corruption of nature.
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. (Romans 1:26-27, ESV throughout)
As we see in Paul’s argument, the passions themselves are what are dishonorable and a form of judgement, not the cause. God, in judgement for the rebellious nature of humanity, allowed people to corrupt the human nature such that it would bring about dishonorable (in view here is homosexuality, but I think that a broader view would include passions for other sinful things such as drugs, greed, heterosexual lust, etc, see Rom. 1:29-30) passions. Furthermore, we see that it is not just the orientation of a person or their passions (which I think Paul would hardly say are voluntary) that are dishonorable, but the acts themselves. When we read further we see this confirmed.
And since they did not see fit to acknowledge God, God gave them up to a debased mind to do what ought not to be done. (Romans 1:28)
Again, Paul notes that because of their refusal to acknowledge God, that God allows the people to corrupt their own thoughts, natures, and passions in order to allow them to do things that “ought not to be done.”
See, the Orientation Argument wants to ground the idea of what is right or wrong within the internal nature of a person. If a person is attracted to members of the same gender, then it is right for them to engage in the full range of sexual behavior with that person. However, this is simply sanctified relativism. What is right, according to this argument, is right because it is right for that person. They would never extend this argument to other sexual orientations, nor would they extend the argument to the “orientation” of most heterosexuals to seek multiple partners. However, Paul does not establish what is right or wrong by appealing to the nature of individual persons, rather he assumes that God has established moral acts, and immoral acts, and regardless of what a person’s orientation, passions, or mind tell them what to do, the acts themselves are seen here as that which “ought not to be done.”