A little ink, whether etched upon our skin or upon a piece of paper, can lead a discussion, with another person, into the realms of what it means to have a righteous relationship with the one true God, but often the story behind the ink and what it means get perverted because of what the inked person conveys because of what is written upon their hearts, which is not always Godly.
A better opening for evangelism, after the small talk of getting to know the other person a little, is simple the question, "What or how are you feeling about your relationship with the God that you are presently worshipping at this very moment?"
This question is not about, "Are you saved through your relationship with Jesus Christ?" which can be very confrontational to the person being asked, but it rather gives the other person an opening to tell us about their relationship that they may have with the God/god that they presently are in relationship with. The conversation can then lead to an opening where we can talk about our relationship with the God that we worship and the impact that this relationship has on our lives as it allows us to talk about what God has "inked"/written upon our own hearts.
This is the invisibly "inked" relational conditions that God has with us that requires us to be open and honest about our true relationship with God to others.
A tattoo may help us to look like others, but it is the unfading inked words of God upon our hearts that truly sets us apart forever.
Shalom