23 “When you come into the land and plant any kind of tree for food, then you shall regard its fruit as forbidden. Three years it shall be forbidden to you; it must not be eaten. 24 And in the fourth year all its fruit shall be holy, an offering of praise to the Lord. 25 But in the fifth year you may eat of its fruit, to increase its yield for you: I am the Lord your God.26 “You shall not eat any flesh with the blood in it. You shall not interpret omens or tell fortunes. 27 You shall not round off the hair on your temples or mar the edges of your beard. 28 You shall not make any cuts on your body for the dead or tattoo yourselves: I am the Lord (Lev 19:23-28).
Based on Lev 19:28, some Christians are opposed to tattoos and body-piercing.
However, as you can see from the larger context, Lev 19 contains a number of commands and prohibitions which Christians ignore. This goes to the perennial issue of how much OT law carries over into the new covenant.
One facile solution is to say that all this is mooted by the new covenant. But that's too simple and radical. Take the prohibition against divination in v26b.
Because Leviticus is a part of the Mosaic covenant, and has a particular emphasis on cultic holiness, there's no presumption that Levitical commands and prohibitions extend into the new covenant. But that doesn't mean we're free to dismiss any and all Levitical injunctions without due consideration.
It isn't necessary inconsistent to obey some Levitical injunctions and disregard others. For it depends on whether there are different principles connecting various injunctions, and whether some of those principles were temporary while other principles are permanent. Consistency would be measured, not by consistently obeying or ignoring all the injunctions, but consistency with the principle that some share in common.
Why are some of these activities forbidden in the first place? In the case of body-piercing, it's not a general prohibition. Rather, it specifies the motivation: body-piercing as a mourning ceremony for the dead (cf. Deut 14:16). That's also the principle which underlies the prohibition about cutting hair and beards (cf. Deut 14:1).
Strictly speaking, the prohibition against body-piercing contradicts the prohibition against Exod 21:6 & Deut 15:17. So the prohibition is not absolute, even according to the Mosaic covenant.
At the same time, because God made the body (Gen 1:26-28), OT ethics would be opposed to mutilation. That would violate the integrity of the body. We should avoid disfiguring the body through dramatic body-modification. It is, in part, a question of degree.
The fact that some of these forbidden activities are associated with pagan rites suggests that that's why tattooing (or body-painting) is forbidden in v28. Indeed, one commentator says:
Porter reports that in pagan societies in the ANE worshippers bore marks on their bodies as a sign of being devotees of a particular deity. J. Currid, Leviticus, 260-61.
If so, the prohibition is not general or absolute, but in reference to tattooing your body as a sign that you belong to the cult of a pagan deity. He (or she) is your patron god (or goddess). It is not tattooing, per se, but the intent, that's forbidden.
In addition, some of these activities are forbidden, not merely because they are adventitiously associated with pagan practice. Rather, due to syncretism among ancient Israelites, these activities indicate conscious participation in heathen rites. They are deliberately imitating their pagan neighbors. The action is meant to be an act of religious devotion to a heathen deity. Apart from that illicit motivation, it might be innocent.
Finally, there can be the danger of emulating unbelievers just to fit in. To be with it. To be accepted.
But with these caveats in mind, I don't think Lev 19:18 represents a timeless prohibition against tattoos. Indeed, tattoos can sometimes be countercultural, rather than a mark of cultural assimilation. Christian tattoos can be both a witness and a statement of separation from the prevailing social mores.