I have heard the sacrament of baptism described as an invisible tattoo of God's ownership using as an illustration the tattoos of Nazi concentration camp survivors. I think this is unfortunate -- I know the speaker meant it in contrast to the Nazis, but still the comparison of turning people into numbers & trying to remove their humanity remains. I thought at first a brand is better, because it's for property the rancher cares more about than the Nazis did their deathbound wards. However, that's wrong also because it's for property meant to be turned into food.
A better picture is that of jewelry for a bride. Song of Solomon 1:10-11 "Your cheeks are beautiful with earrings, your neck with strings of jewels. We will make you earrings of gold, studded with silver." Abraham's servant gave Rebekah a nose ring, claiming her as a wife for Isaac. A man gives likes to look at his wife wearing the jewelry he gave her as a beautiful reminder of their bond.
