What is the meaning behind "Love" and "Hate" that is tattooed on someone's fingers?

Often people do that to express a dichotomy.

https://en.wikipedia.org/wiki/Dichotomy

For example, "The Reverend Harry Powell was an itinerant preacher, con artist and serial killer with a switchblade and a puritanical hatred of women and sex. He had the words "LOVE" and "HATE" tattooed on his knuckles and would use them in a sermon about the internal struggle between good and evil. He would spread the gospel until money ran thin, at which point he would gain the trust of wealthy widows, marry them and kill them for their money. He would then run off (often in a stolen car) and repeat the process. He never thought God would forsake him for his crimes; after all, he was doing God's work and "God's book was full of killin's", as he put it."


https://en.wikipedia.org/wiki/Reverend_Harry_Powell