Mat 15:19 For out of the heart proceed evil thoughts, murders, adulteries, fornications, thefts, false witness, blasphemies:

"'Evil thoughts" is a bit of a mistranslation. The term is closer to "worthless arguments." However, both versions represent the mental realm since Christ uses words as a symbol for thoughts. What Christ is saying is that our feelings, which come from our relationships, shape our thinking. Them these thoughts then create our actions. Good relationships lead to good thoughts and good actions. Bad relationships lead to bad thoughts and destructive actions. Kind of an interesting insight that is easy to miss.

Christ is the word made flesh, that is, the thought of God given physical existence. He is teaching an intellectual idea, but the idea is our relationships, that is, how we treat people is more important that our intellectual endeavorts.

"Evil" is ponêros which means more "worthless" or "burdensome."
"Thoughts" is dialogismos , which means "debate," "argument," and "discussion." It can also mean "balancing of accounts," "calculation," and it is the term for a "circuit court." It isn't usually translated as "thought."
"Murder" is phonos . "Adultery" is moicheia. "Fornication" is porneia , which means "prostitution" for a woman and "fornication" for a man. "Theft" is klopê. "False witness" is pseudomarturia.