One little word in Greek (and, then, a few words in English—depending on the translation) makes all the difference for how we understand a believer’s relationship to sin.
In Hebrews we’re told that our high priest (Jesus) is able to know what we’re going through when it comes to temptation and sin because he went through it. We’re told that he was tempted in every way we are with one stark difference—he did not sin.