Did the religion of Christianity arise in AD70?

The problem with historical hypotheses is that evidence is highly subjective. What evidence would you accept for or against your hypothesis?

If you would accept the Bible, your hypothesis will not stand, evidently. But what exact version of the Bible? What translation, what documents, and so on, and so on.

Personally, I love this historical hypothesising, as it always can help to gain a deeper understanding of history. But I know for a fact that I cannot know anything for a fact if I don’t start with some paradigm, some axioms if you will, that in itself cannot be proven.

To me, that paradigm could be roughly named “Catholic faith” or “Christian faith”. For me as a catholic your hypothesis is interesting, helps thinking about the first century of our timetable, but it cannot be accepted as true. Simple evidence: it cannot be reconciled with my faith.

To someone whose paradigm might be roughly named “post Cartesian science” or even “post Wittgensteinian science” my position would be utterly ridiculous. The idea of a man, being Son of God, crucified to atone for man’s sins, being resurrected must be very close to madness. On the other hand, the idea of a religion being deprived of it’s only temple where a offerings-cult was central to that religion, surviving by two different routes, a cult around a god-man making the final offering on the one hand and a cult around study of the words and the law of their god while lacking a temple in the expectation of the resurrection of that temple, would make perfect sense.

I am afraid your question, however fascinating, will never get an answer that goes beyond a starting position. In this, your question is circular. Evidence for your hypothesis is acceptable for whom already could accept your hypothesis without evidence. Evidence against your hypothesis is acceptable for whom already would reject your hypothesis without evidence.

The term "Christianity" is most often used in the very-broad religious sense, rather than with theological specificity. For orthodox (small o) Christians, the special advent of God the Holy Spirit (promised in John 16) to the elect Heavenly People of God is recorded in Chapter 2 of the Book of Acts. For Christians, this unique (Day of Pentecost) coincided with the Jewish Feast of Shavuot being observed by the elect Earthly Peoples of God - Israel/Judaism). Many significant events occurred on the Day of Pentecost.

OP the religion of Christianity arose as a result of the destruction of the Jewish temple and the Jewish priesthood by the Romans in the year 70. This date marks the inception of the religion and not AD30-33 when Jesus was supposedly crucified.

Given that the two religions, CHristianity and Judaism, continue to exist, the idea that Christianity was somehow invented as an alternative to the Temple destruction is, at best, an odd one.

If one reads the Book of Acts, we find numerous references to Christianity (and to Judaism) as existing.

Acts 2 Pentecost, pouring out of Spirit Peter's sermon, mentioning numerous fulfilled prophecies

Acts 6, choosing of seven

And the word of God increased; and the number of the disciples multiplied in Jerusalem greatly; and a great company of the [Levitical] priests were obedient to the faith.

Acts 8, Christianity spreads out from Jerusalem and Alexandria

Acts 10, Christianity spreads to Gentiles

Acts 11, the name Christians is first used, used to differentiate from Judaism

Acts 15, conflict between the two religions on "how to be saved"

Acts 16-28, spreading of Christianity

OP it is asserted that the life of Jesus as portrayed in the gospels was invented to explain how the religion arose, but it actually arose as a consequence of the interplay of expectation and traumatic events consistent with normal human behaviour.

Per Daniel's 70 weeks, the expectation of Messiah was high and fulfilled within its time frame. This was 40 years (symbolic of testing) prior to Temple destruction.

So, to answer the OP, Christianity existed from Christ's resurrection and ascension and Pentecost through today. The destruction of the Temple was foretold by Christ, which meaning is a different question.

Several verses in the Bible make specific reference to Christians. One even tells us the origin of the word.

And when he had found him, he brought him unto Antioch. And it came to pass, that a whole year they assembled themselves with the church, and taught much people. And the disciples were called Christians first in Antioch. (Acts 11:26, KJV)

Then Agrippa said unto Paul, Almost thou persuadest me to be a Christian. (Acts 26:28, KJV)

Yet if any man suffer as a Christian, let him not be ashamed; but let him glorify God on this behalf. (1 Peter 4:16, KJV)

According to the Bible, then, Christians were not first called by this name in Jerusalem, but in Antioch. Acts chapters 9-11 detail events that happened in short succession, beginning with Saul's conversion on the road to Damascus, shortly after the stoning of Stephen in AD 34. Chapter 11 speaks of the passage of a year's time during which the believers met together in Antioch. This is where they acquired the name "Christians." Following the Biblical story, this must have occurred before AD 40, probably close to AD 35 or AD 36, within a year or two after Saul's/Paul's conversion.

Agrippa, speaking to Paul before his journey to Rome used the word, so it must have been already widespread by then. Paul's exact date of death is not known, but the latest date that most scholars accept for it puts it in AD 67.

And Peter used the term--one of the earlier disciples to be martyred. According to the Encyclopaedia Britannica, Peter died in AD 64.

St. Peter is believed to have died as a martyr for his faith. Although his death is not described in Scripture, numerous writers of the time (or shortly thereafter) described his death as having occurred in Rome during the reign of the emperor Nero in 64 CE. LINK

This clearly predates AD 70.

Conclusion

The term "Christians" arose well before AD 70. Its converts began assembling to meet together very early, during the persecution of the Jews against them in which many were martyred. During this time of trial, and testing of their faith, their beliefs were strengthened. One does not willingly die for a teaching that one only half believes.