I agree that a Christian should not tattoo their body. Why would you want to put graffiti on the temple of God? If God wanted you to be marked colorfully he would have created you that way. He did so for many animals in his creation but that is not what he intended for man. His word says
 
Le 19:28 - Ye shall not make any cuttings in your flesh for the dead, nor print any marks upon you: I am the LORD.
 
If you have followed the crowd and had your body tattooed and marked since being saved...
 
 Ac 8:22 - Repent therefore of this thy wickedness, and pray God, if perhaps the thought of thine heart may be forgiven thee