Yes, it’s a sin.
For it is written, "Do not cut your bodies for the dead, and do not mark your skin with tattoos. I am the LORD (Leviticus 19:28). To mark your skin with tattoos is a sin just as lying, greediness, selfishness etcare sins. For it is writing “All wrongdoing is sin, but there is sin that does not lead to death (1 John 5:17). To mark your skin with tattoos is a wrong doing. To mark your skin with tattoos is gratifying the flesh, and the Bible says we should not gratify the flesh.
For it is written, “So I say, walk by the Spirit, and you will not gratify the desires of the flesh. For the flesh desires what is contrary to the Spirit, and the Spirit what is contrary to the flesh. They are in conflict with each other, so that you are not to do whatever[a] you want. But if you are led by the Spirit, you are not under the law. The acts of the flesh are obvious: sexual immorality, impurity and debauchery; idolatry and witchcraft; hatred, discord, jealousy, fits of rage, selfish ambition, dissensions, factions and envy; drunkenness, orgies, and the like. I warn you, as I did before, that those who live like this will not inherit the kingdom of God. But the fruit of the Spirit is love, joy, peace, forbearance, kindness, goodness, faithfulness, gentleness and self-control. Against such things there is no law. Those who belong to Christ Jesus have crucified the flesh with its passions and desires. Since we live by the Spirit, let us keep in step with the Spirit (Galatians 5:16-25)
Finally, it is written, “All scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness (2 Timothy 3:16).”