At what point did Jesus’ “last name” Christ become exactly that, his last name. From my understanding the word Christ is derived from the Greek word khristos “the anointed”.
Why don’t we say Jesus the Anointed?
Aren’t you asking, “when did “Christ” become a surname”?
It has always been a title. Unless of course, you are Jesus H. Christ .
I like to refer to him as Joshua bar-Joseph, myself.
Or Jo-Bob, for short.
SHouldn’t that be Joshua bar-Yahweh? 
Perhaps I wasn’t clear in the OP.
In greek they say (translated for your convienence) “Jesus the Anointed” (Khristos)
Before English speaking humans got wind of this guy, the word “Christ” had NO meaning.
When we say in English “Jesus Christ” we are saying exactly that. NOT Jesus the Annointed.
Why not? I’ve never been taught that the word “Christ” really means Anointed.
Sorry, I think you are still unclear about which part you are asking about. I could be wrong. I need sleep.
We were taught that of course theoretically we should always refer to Jesus “the Christ”, since it was literally Jesus “the anointed one”. But English speakers being the lazy lot that we are, the “the” quickly disappeared.
That’s Mr. Christ to you. :mad:
English appropriates quite many foreign terms and reuses them. Always has. It is not at all remarkable that Christ has become an English word.
This happened long before the English language even existed. Paul uses “Jesus Christ” and “Christ Jesus” as names for Jesus sometime around 50 AD. “Christ” (which is the Greek translation of “Messiah”, both of which mean “anointed”) was well on its way to being a name already at that time.
So we took it from Jesus and gave it to Smokey Bear.
It all evens out.
Howzabout a little Latin?
Domine Jesu Christe, Rex gloriae…
I’m not quite sure what point you’re making, given that Latin doesn’t have a definite article.