Celsus claims that only SOME (τίνες) Christians believed that Christ was lived on earth

[Giuseppe]

I am saying that everything Celsus says in the name of these "certain Christians" (one group) comprises one statement: "there has already descended upon the earth a certain god or son of a god who will make the inhabitants of the earth righteous."

my simple point is that, insofar Celsus talks only about a sub-group of Christians (in virtue of the word "certain") as having that belief, then eo ipso he is assuming NECESSARILY the existence of the other Christian sub-group: other Christians who denied precisely the statement: "there has already descended upon the earth a certain god or son of a god who will make the inhabitants of the earth righteous".

About the possible identity of this implicit sub-group, I can only think about Christians who adored a Christ who was crucified not on earth.

What about the group of Christians who thought that Jesus was simply a "man of men", which you asked about recently in your Justin Martyr thread? Might they be a possible sub-group here?

Obviously, the ebionites (the kind of Christians you are alluding, i.e. believers that the Messiah Jesus was a mere man who will return as risen and exalted by God) have to be classified among the "certain Christians" who believe that:

"there has already descended upon the earth a certain god or son of a god who will make the inhabitants of the earth righteous"

So no, the only implicit sub-group I am talking about is the sub-group according to which the Son of God has not still descended on earth, despite of his being crucified (that is equivalent to say: their Son of God was not crucified on earth).

[GakuseiDon]

Obviously, the ebionites (the kind of Christians you are alluding, i.e. believers that the Messiah Jesus was a mere man who will return as risen and exalted by God) have to be classified among the "certain Christians" who believe that:

"there has already descended upon the earth a certain god or son of a god who will make the inhabitants of the earth righteous"

But the Christians Justin Martyr was referring to apparently believed that Jesus was just a man. He had been born (presumably to Joseph and Mary) just like any other man. In other words, their Jesus had not descended to earth from heaven at all.

[Giuseppe]

Obviously, the ebionites (the kind of Christians you are alluding, i.e. believers that the Messiah Jesus was a mere man who will return as risen and exalted by God) have to be classified among the "certain Christians" who believe that:

"there has already descended upon the earth a certain god or son of a god who will make the inhabitants of the earth righteous"

But the Christians Justin Martyr was referring to apparently believed that Jesus was just a man. He had been born (presumably to Joseph and Mary) just like any other man. In other words, their Jesus had not descended to earth from heaven at all.

Absurd. The implication of the your premise is that these Christians believed that the coming Destroyer was not the same mere man Jesus lived in the past and now exalted by God. In that case they would be not Christians at all, against Justin's claim that they were.

[GakuseiDon]

Giuseppe, I realise that English isn't your first language. Please note that "the coming (descending) god" is something that will happen in the future, while an "already descended god" is something that happened in the past. Christians who believed that Jesus was born just a man didn't believe he had descended from heaven as a pre-existing being.

Celsus takes a standard philosopher's view that the idea that a perfect God had to descend to achieve some purpose is "a most shameless assertion", for reasons supplied by Origen in the link you provided in your OP:
1. If such a god descended to learn what was going on on earth, then it suggests that the god was ignorant and couldn't learn what was happening on earth from heaven.
2. If it descended to improve the people on earth, then it suggests that the being lacked the divine power to do this from heaven.

Origen responds to those points. I'd strongly recommend that you read through Origen, since getting an understanding of ancient thought might help you to find stronger arguments and reject weaker arguments for your theories. Understanding the difference between past and future is also very useful.

[Giuseppe]

Christians who believed that Jesus was born just a man didn't believe he had descended from heaven as a pre-existing being.

really? Are you really advancing the absurd idea that once the mere man (lived in the past) was exalted by God after his resurrection - as the ebionites believed that that mere man was risen - then he didn't cease to be a mere man? Can you give me examples of men who rise (=are exalted by God) and continue to be men (!) and not divine beings?
I doubt you can. It seems that you are evidently ignorant of the ebionite view. A man who rises becomes eo ipso a divine being, on the specific case, a Son of God. As such, he can be called as "Son of God" also in reference to his past earthly existence as mere man.

Congrats, GDon, to show again and again evidence of your innate apologetical reluctance to classify the ebionites among the Christians who believed that the Son of God was ALREADY descended in the past.

Origen responds to those points. I'd strongly recommend that you read through Origen,

I reject entirely your advice, since the Origen's views on Celsus count as your views on Celsus: zero.

[Giuseppe]

My explicative note of the passage reads:

In the text "certain" (tinés) does not refer to a particular sect; all the Christians shared the view that the son of God had already come down to earth: Völker, 1928, p. 65; Nock, 1961, p. 585 = p. 933

(my translation and my bold)

"All" means: the ebionites, also.

Something that the Christian apologist GakuseiDon should recognize, if only he was intellectually honest.

[GakuseiDon]

You have defeated me again, Giuseppe! All I can do is stand back in astonishment and admiration, and even a bit of fondness. Please carry on.