Many Christians aren't quite sure what to make of the Old Testament, having been taught that the laws of the OT are not applicable to them (based largely on Romans 6:14). Which parts apply and which parts don't?
I find it mildly humorous that some conservative (better: fundamentalist) criticisms of cultural practices find their supposed biblical basis in OT laws that would most certainly be abrogated by Rom 6:14.
Let's take, for example, the fundamentalist aversion to tattoos because, well, tattoos are just unbiblical. There might be plenty of perfectly rational reasons to NOT get a tattoo (will you like it in 30 years, what if you break up, etc.), but "because the Bible says it's wrong" isn't one of them.
The biblical injunction against tattoos is found in Leviticus 19 (one of my personal favorites for devotional reading).
Leviticus 19:28 (ESV): You shall not make any cuts on your body for the dead or tattoo yourselves: I am the Lord.
That seems straightforward enough. "You shall not tattoo yourselves." But wait, what's all this "cuts on your body for the dead" stuff about? I have a great idea . . . let's look at the context.
Leviticus 19:26-28 (ESV): "You shall not eat any flesh with the blood in it. You shall not interpret omens or tell fortunes.  You shall not round off the hair on your temples or mar the edges of your beard.  You shall not make any cuts on your body for the dead or tattoo yourselves: I am the Lord.
Wow . . . reading verses 27-28 together is really paradoxical for fundamentalists. First, don't cut your hair or beard (i.e., look like a hippy - anathema to a fundamentalist who must be clean-shaven with short hair). Second, don't tattoo yourselves. Long hair is good; tattoos are bad. Mind bending, isn't it?
It's funny that some OT laws are invoked to explain cultural preferences, but most are ignored as no longer applicable. For example, when's the last time you checked your garments to avoid a cotton/polyester blend?
Leviticus 19:19 (ESV): "You shall keep my statutes. You shall not let your cattle breed with a different kind. You shall not sow your field with two kinds of seed, nor shall you wear a garment of cloth made of two kinds of material.
Work for a bank? Is it ethical to be charging interest, especially to members of your own religious community?
Deut. 23:19 (ESV): "You shall not charge interest on loans to your brother, interest on money, interest on food, interest on anything that is lent for interest.
The fact that these laws are no longer relevant today (at least for most Christian communities) doesn't mean that they shouldn't be read. They can still teach us something about how to read our Bibles and about what issues were important to the biblical writers.
It's important for our passage on tattoos to notice what the biblical writer was really concerned with. It wasn't tattooing per se. Let's go back to the "cuts for the dead" issue. It seems like the writer of Lev 19:26-28 was concerned with magic and idol worship. I think it's safe to assume that eating flesh with the blood, interpreting omens, telling fortunes, cutting hair, cutting the body for the dead, and tattooing were all practices associated with necromancers, witches, mediums and wizards. In fact, I'd say that Lev 19:29-31 continues with a concern for practices associated with idol worship and magic (based on the explicit return of that topic in Lev 19:31).
Anyone with some experience reading ANE ritual texts care to back me up? Are those ritual or cultic practices described in Lev 19:26-31?
So if you're a tattooed Christian, it's ok. God forgives you.