I find it hard to believe that a Christian would be disobedient in this respect unless it is done in ignorance. But surely before making such a serious decision as a tattoo, a believer would no do this without much prayer and searching the Word of God.
Leviticus 19:28 KJV  Ye shall not make any cuttings in your flesh for the dead, nor print any marks upon you: I am the Lord .
a List wrote: "Church Logo Tattoos?" Arminian church - "In god we trust only when HE asks our permission first." Liberal church - "In me I trust because I am as nice as god might be if I knew him." Baptist church - "In deep dunking I trust since sprinkling doesn't reach all the parts." Reformed church - "In God we trust because He elected us." Presbyterian church - "in God we trust because the Holy Spirit guides us."
Reformed and Presbyterian should read:
"We trust in the water used for sprinkling in our baptism to save us because it turns into pixie water and makes us and our children the elect of God.
Who needs God when we can determine our own election.
Get Calvin or get lost."
(Look up Sacerdotal and compare with the WCF. An element of Romanism that was retained. )
For Baptists, it is just a memorial and a testimony to the Lord's goodness in converting the person being baptized. Hence no pixie magic!