Should have added verse 17. Both should be read as one verse.
How do you write anything on your forehead?
16
For God so loved the world that He gave His one and only Son, that everyone who believes in Him shall not perish but have eternal life.
17
For God did not send His Son into the world to condemn the world, but to save the world through Him.
18
Whoever believes in Him is not condemned, but whoever does not believe is already condemned, because he has not believed in the name of God’s one and only Son
From the looks of all his other tattoos it was probably the only blank space left on his body to write anything