Wrong is Progressive

I was just reading a letter that J.R.R Tolkien wrote to C. S. Lewis concerning Lewis’ book Mere Christianity and this section stuck out for me

And wrong behavior (if it is really wrong on universal principles) is progressive, always: it never stops at being “not very good,” “second best”—it either reforms, or goes on to third-rate, bad, abominable.

I thought it was good point that seems to be true.