Leviticus 19:28: "You shall not make any cuttings in your flesh for the dead, nor shall you make in yourselves any figures or marks: I am the Lord"
It should be considered as mutilation of the body in contravention of the Fifth Commandment. The fact that the tattoo may be of a religious object does not justify the practice. Exhibitionism is intrinsically un-Catholic, falling short of the virtue of humility. Would the Lord Jesus Christ have had a tattoo? The Blessed Virgin Mary? Of course not. How do we know? Because they would both have perfectly kept the law in all its points, including "nor shall you make in yourselves any figures or marks".
There is another argument against the practice, which relates to the Fifth Commandment, which forbids unnecessary harming of one's body, the Temple of the Holy Ghost, as St. Paul calls it. Catholic moral theology teaches that by the Principle of Totality, a person is not permitted to authorize the mutilation of his own body except for the benefit of the whole body by the principle of totality. Mutilation of the body can be justified only on the supposition that it is necessary or useful toward obtaining some just physical benefit (as an amputation of a diseased leg to prevent the spread of gangrene).
The practice of tattooing often involves an unnecessary medical risk of acquiring the dangerous virus Hepatitis C. This virus, once acquired through such practices as tattooing, can erupt virulently, or it can lie dormant in the body for twenty or more years after the tattooing incident. Hepatitis can destroy the liver and thus weaken the body until it dies in agony.
You should not get a tattoo or piercing. The Bible is pretty clear on the matter:
Leviticus 19:28: “You shall not make any cuttings in your flesh, for the dead, neither shall you make in yourselves any figures or marks: I am the Lord.”
1 Corinthians 3:16-17: "Know you not, that you are the temple of God, and that the Spirit of God dwelleth in you? But if any man violate the temple of God, him shall God destroy. For the temple of God is holy, which you are."
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