The Scriptures were inspired by God, yes, and we are not to subtract from them. But nor are we to add to them.
Let us be clear about the Law that is in the Old Testament.
There are laws given to Noah: we can eat animals now (unlike before the flood) - ALL animals - there is no "kosher" - but we are not to kill or shed the blood of men.
There is a law against adultery before Sinai - God sickened the people of both Pharaoh and Abimelek when those two unwittingly took Sarai into their households because she and Abraham pretended not to be married.
To the extent that there were other laws also, God didn't inspire anybody to write it down.
Then we move forward to the Sinai Covenant. The Covenant says from the beginning exactly who it was for: the Israelites there at Sinai, and their descendants who keep the law. It is explicit what the promise is: do all of this, and you get a secure farm in Israel and a prosperous and healthy family.
And that is all.
What is NOT anywhere in that covenant are all of these things:
(1) A promise (or even a mention) of life after death.
(2) A promise of resurrection.
(3) A promise of "going to heaven" after death.
(4) A promise addressed to any male who is not a circumcised heir of an Israelite present at Mount Sinai keeping the commandments within the specifically circumscribed land of Israel.
So, if you were an Israelite and got a tattoo, you might well be banished from Israel, and lose your farm. Your eternal life? There is no promise, or even reference to, eternal life anywhere in the Torah. It is adding to Scripture to attempt to graft the promise of eternal life onto the Old Covenant. The only thing promised at Sinai for obedience to all of those laws was a farm in Israel. Nothing more.
To see more there, like going to Heaven, or that a Gentile "sins" by not doing something or doing something there, is to add to Scripture.
The Ten Commandments as given at Sinai were exclusively for the Jews. They did not apply to anybody else before, and they have never applied since.
That was made very clear at the Council of Jerusalem too. Now we've skipped together to the New Testament. The question was: Do Christians have to follow the Torah. And the unequivocal answer was NO. Instead, a simple set of laws was given for Gentiles: no idolatry, abstain from blood - nothing more. This does not REPLACE the Torah - the Torah never, ever (ever) applied in any form, including the Ten Commandments, to anybody but Hebrews living in Israel, and the only consequence stated in the Torah to a Hebrew for disobedience of any of it (including the Ten Commandments) was loss of the farm in Israel.
That's what the Scripture SAYS. To make the Torah apply to Christians was specifically rejected by the Apostles in the New Testament.
So, we cannot ADD to Scripture by asserting that even one law of Sinai was imposed on us: it was not. Nor can we SUBTRACT from Scripture by asserting that those laws - even if they did apply - still do, because the Apostles themselves, including Paul, assembled at Jerusalem, clearly stated no.
That should be that.
Jesus said to follow HIM, and HE gave a series of precepts. On the last page of Scripture he twice says what will earn a man the Lake of Fire at final judgment: killing, lying, sexual immorality (a broad thing that encompasses bestiality and fornication and adultery), idolatry, "pharmakeia", and a few other things.
Jesus said a few other things. He summarized the essence of all of the Jewish Law: Love your neighbor as yourself and love God above all. He also gave a new and specific precept: do unto others as you would have them do unto you.
And Jesus said what you had to do to be forgiven your sins by the Father. He didn't say sacrifice a goat. He said that to be forgiven your sins, you must forgive other men the sins they have committed against you. If you forgive, you will be forgiven by the Father, but if you refuse to forgive, you will not be forgiven either.
Note very well that Jesus never subtracted that requirement for forgiveness from sin.
Christian traditions say that to be forgiven from sin you can:
(A) Ask Christ to be your personal Lord and Savior, or
(B) Confess your sins to a duly ordained priest in the Apostolic succession and obtain penance and absolution.
That's swell, and sits alongside of the Old Testament's
(C) Bring a sheep, or a goat, or two turtledoves.
But that's adding to and subtracting from Scripture.
What Jesus said was
(D) To be forgiven your sins by the Father, you must forgive other men their sins against you. If you forgive, you shall be forgiven, but if you do not forgive, neither will you be forgiven.
D is the only right answer, because it is what Jesus SAID.
Jesus said "Follow ME".
The Father, speaking from heaven, told the crowd assembled: "This is my Son, listen to him."
So, there you have it: the commandment, the Torah, the law for everybody in the world who wants to pass final judgment and enter the City of God someday (as opposed to those who want a farm in Israel while they live): Follow Jesus, obey HIS commandments, love others, and forgive. That is the Torah for all NOW.
Tattoos? Jesus was silent on tattoos. Therefore, spiritually, it is entirely up to you. You may query why God didn't want the Hebrews to wear tattoos. And you may also wonder why God didn't supply you with a tattoo at birth if he thought they were good for you. But you add to Scripture and traffic in a lie if you say that God forbids people from getting tattoos, and it's a sin if you do. God forbade the circumcised descendants of Sinai from getting tattoos, and if they did, they lost the farm.
That deal was never for Gentiles in the first place. The Law of Sinai is instructive into what God thinks, but it is not a law for you and me, and never was. The Law of Jesus is what we need to be listening to.