A huge portion of Christianity is focused on the idea of Jesus being the perfect, sinless sacrifice. Although, I'm not sure if this is as big in Eastern Orthodox. The perfect/sinless idea seems very tied into the penal substitution idea, which Jesus taking our place, and accomplishing what we cannot do. So I'm not sure I can say that Christianity as a whole is incredibly focused on that narrow idea of sacrifice, or if it's just Evangelical Christianity.
But I'm wondering what this perfection is based on. Before people go quoting me the letters, such as Peter or Paul, where they push forth the idea of Jesus knowing no sin becoming sin for us, or Jesus tempted like us yet not sinning, I'm wondering what actions the claim is based on. Too often, it feels that we are told Jesus is perfect because Peter says so. Or Paul says so. But I don't see them pushing forth any "proof." I don't see them saying, "Jesus is perfect because he did such and such." Rather, the idea is simply that Jesus was sinless, no proof required.
However, if we took the Gospels, which are the only accounts we have of day to day actions, would we reach the same conclusion? If we took the Gospels and replaced all the names, and then gave them to someone who lacked familiarity with the stories, would the person conclude that the Jesus character behaved perfectly? Would any of us?
Or do we all just say that Jesus is perfect because that's the assumption? Because that's what the New Testament letters tell us?
What actions are used to determine the perfection of Jesus?