How do you mean?
There is a sense in which if a person anticipates that a faith based tattoo design (Christian fish sign <>< on arm, etc.) will lead to many witness conversations, then going ahead and getting it might be described as an act of faith.
From my own experience, whenever I meet a new person, we will talk at some moment about God, because both christians and non-believers love this topic. The shy young person that you was talking about in another post, should put her faith in God, not into a tattoo. This is what I don`t like about tattoes: they are based on complexes, on fears, on lack of faith, or on the contrary, on pride, on self-glory, on rebellion etc. I also don`t agree with christian tattoes (especially those that portray Jesus Christ) because they seem to take God in vain. Christianity is to be lived, not exposed on our bodies.
My church is against tattoes not because they are inherently bad, but because through the tattoo (and other wordly things) we preoccupy ourselves with vain things. What is our main goal? Salvation and growing into the likeness of God. Is a tattoo going to lead me there? I doubt it.