The essential point of evoking scriptures in any and all arguments is to support one’s religious claims with what is supposedly larger, older, smarter and therefore, objective and true. Though there is an enormous number of scriptural arguments, there is rarely a need to delve into the inner workings of each one in order to refute it.
Pretty much any scriptural argument can be nullified by pointing out the fundamental problem of subjectivity at its core. The reason why this nullifies any scriptural argument is because of why the scriptures were evoked in the first place – in order to establish an objective basis. Therefore, all you need to do is deflate the supposed objectivity of a biblical argument, and what is the religious apologist left with – just their own illogical and subjective opinion.
The issue of subjectivity actually takes two forms, which are both worth pointing out:
1. There is no objective value to the scriptures themselves; which is to say that there is nothing more or less meaningful about the Judeo-Christian bible than there is about the Qur’an, the Bhagavad Gita, or the Buddhist sutras (to say nothing of the fantasy writings of Joseph Smith and L. Ron Hubbard). Vastly different and mutually exclusive writings can’t all be correct at the same time, and any subjective argument for or against one is as good as any argument for or against any of the others. For the sake of economy, and at the risk of making this simple point a bit harsher than it otherwise has to be, I sometimes point out that an anonymously written, edited and translated collection of Bronze and Iron aged tribal Middle Eastern scriptures – scriptures that start with a talking snake in a magic garden, and end with a seven headed monster that destroys the world – might not necessarily be all that objectively valid in support of, say, an argument against evolution, same sex marriage or stem cell research.
2. As if it were not enough for the scriptures themselves to be subjectively compromised, the person who is promoting a scriptural argument – and this applies to any and all people promoting scriptural arguments – is injecting their own subjectivity into the mix. To show how this is so, it is enough to point out any of the scriptural laws and prohibitions that the speaker does NOT follow while they promote others that they do. If, for example, one is to point out that Mosaic law prohibits homosexual relations (Leviticus 18:22, Leviticus 20:13), one cannot simply ignore the fact that the same set of laws also prohibit the eating of pork (Leviticus 11:7-8). For a person to promote one law while discarding another is to directly inject their own subjectivity into the mix. It is important to keep in mind that nowhere in the scriptures is permission given to cherry pick which laws to follow and which to ignore. Christian apologists who would point out that Jesus, in the New Testament, has given certain dispensations from following some Mosaic laws, have to square this with Jesus’ stern and contradictory statement about not a dot of Old Testament law being relaxed till the end of days (Matthew 5:18-19). Moderate religious apologists often claim that the scriptures are not supposed to be taken literally, and that they are subject to various god inspired interpretations in order to fit them to the changing spirit of the time, but this makes the same subjectivity point in a different way (or not all that different, if you think about it). Quite simply, if you can claim that, say, the fourth commandment (keeping the Sabbath) is to be relaxed, while maintaining that the law prohibiting homosexual relations is to be upheld (though without the capital punishment that is supposed to accompany it), then I can just as easily claim it is the other way around. It really is as simple as that.