The Bible is a wonderful guide to living and, taken as a whole, is so brilliant that I have no doubt it was inspired by God. But some of the rules appear to reflect the time in which it was written. Our knowledge about disease transmission and access to modern medical treatment seems to make some of the guidance obsolete. Also, changing social attitudes make other recommendations appear as anachronisms. For instance, the Bible forbids eating seafood without fins and scales (like lobster and crab) (Leviticus 11:10), advises slaves to obey their masters, even if they are unreasonable (1 Peter 2:17).
I have absolute belief in the words of Jesus and the ten commandments. But I believe that the Bible needs to be viewed holistically and interpreted intelligently. What do others think?
When I saw the title for the thread, I was thinking of replying that the Confessional Lutheran view is to read scripture within its context. Read history as history, metaphor as metaphor, poetry as poetry, etc. That doesn't solve the problem because then some people start arguing that certain parts of Genesis are poetry, but it's still a good starting point.
Second, the Confessional Lutheran view is that scripture is inerrant and the final authority. So, we can seek other sources in cases where the Bible is silent. We can even seek other sources to deepen our understanding of things the Bible does speak about. But when the Bible speaks, it is the final authority.
Finally, though, there is a need to understand scripture in its entirety. Basing theology on a single verse is risky. Not always wrong, but still risky. So, in the context of dietary laws, one needs to consider not only Leviticus but also Mark 2 and Acts 10. Some of the ritualistic meaning behind such things was fulfilled in Christ and is no longer necessary. That can also get dicey, but it's an important principle to understand.
And I think that's more where your question is going. You seem to be asking a specific question about moral precepts, not a general question about scripture. In that regard, much of the "we now know" and talk of holism is a way to excuse the fluid nature of society. The fact that societal morals change does not excuse sinful behavior. If you are a slave, it is still necessary to obey your master. That is
not because the Bible is condoning chattel slavery, and so the need is to understand
why Peter said that - not to dismiss it as archaic.