Mention the prohibition on tattoos in Leviticus 19:6 and it's 98.7% likely that the immediate response will be, "Yeah, and don't wear a cotton/polyester blend, either!"
Now, I take it that the existence of polyester suits is a prima facie case on behalf of mixing fibers. Clearly, a good God would want to save us from such atrocities.
The rejoinder is, of course, a reference to the prohibition on mixed fibers in Leviticus 19:19. If you want to appeal to the prohibition on tattoos to make a case against them, you have to engage--the argument goes--in a pretty selective reading.
There's lots we could make of this regarding the nature and purpose of the holiness laws in Leviticus 19. But given that this realization is new to me, I plan on ruminating on it some more before drawing any fast conclusions.
Matthew Lee Anderson is the Founder and Lead Writer of Mere Orthodoxy. He is the author of Earthen Vessels: Why Our Bodies Matter to our Faith and The End of Our Exploring: A Book about Questioning and the Confidence of Faith. Follow him on Twitter or on Facebook.