The Laws codified were to ensure that the Jews remained 'Holy', which means 'set apart' ... Meaning the pagan influence wasn't considered to be something they were to give in to and still remain God's Holy People. But obviously, they couldn't keep up with it, they lost their way over and over again, and every time they repented, they went right back to the ceremonial procedures and to reading the law out loud for all to hear it. Books of Kings and Chronicles attest to this in the split of the Kingdom after Solomon's death.
As a Christian who has tattoos, I'll 'justify' it like this: My body is a temple (1 Corinthians 6:19) because the Spirit of God Himself indwells me bodily -- Do I have a responsibility to maintain this temple ... Yes. I'm a vegan, and aside from smoking (which I'm trying to quit this week ... again) I have a healthy lifestyle. But this temple does not just exist as flesh, I have a spirit and a mind as well, and I must exercise those as well. So I pray, I read, I seek the clearest perspective I can on reality. But I'm not perfect, and have engaged in 'unhealthy' or risky behavior at times (smoking comes to mind ... and I was angry at God when I did get my tattoo). However, I also know that what Christ did was free me from the Law. I am set apart, considered Holy in God's eyes, now and forevermore because I'm no longer judged according to my deeds, grace has taken over.
1 Corinthians 6:12 and 10:23 state that
"All things are lawful, but not all things are profitable. All things are lawful, but not all things edify."
So there are things I can do (and I do, I'm still being perfected, and will be until death) that all Christians would agree are not beneficial to me, but my salvation does not hang upon it.
Going back to tattoos (and piercings), Deuteronomy 15:17 talks about getting an aul through the ear as a mark that the person was a servant to his master for ever ... Likewise, I would say that tattoos that are of scripture would be the same type of thing (tell me thats not a permanent cut in the body). I'm planning on getting the mermaid tattoo I have covered up in the future with something that will remind me to be a humble servant to God. But until then, I know my salvation is intact, and I try not to shove it (my tattoo, or my freedom) in anyone's face (both tattoos are covered by a short sleeve shirt) because of Paul's statement to the Christians in Corinth (1 Corinthians 8:4-13). If other Christians don't understand that I'm not going to hell because I got a tattoo, then why stir them up?