.. if a tattoo is a CHRISTIAN tattoo it's a great way to make a sort of silent, yet colorful, statement of what we believe. I think that a visual representation of Christ's influence on our lives is a quick way to bring Christ into someone's life who may not think of God otherwise. It serves as a symbol of what I hold as important - Christ!
As long as it's not promoting a sin.. and is meaningful ... why not?
Since I got two Christian tattoos .. I have been able to bring up my beliefs and be a witness to quite a number of people. I think of it as a permanent way to wear a "WWJD" bracelet...
I believe that other tattoos based on other things rather than just God serve as a creative outlet. Just as people wear makeup, others choose to be inked. Perhaps it's just a personal opinion. Whatever it is though, I think it would be wise for anyone getting a tattoo to pray about it and wait to see if God gives guidance.