So the anti-Christian euhemerizers were introducing :
in Zion a stone that causes people to stumble and a rock that makes them fall,
(Romans 9:33)
...since they were scandalized by what
themselves were inventing: a vulgarization in mere human events of the mystery of the cross.
Paul assumes that the Galatians were scandalized by this scandal "put in Zion", also:
You foolish Galatians! Who has bewitched you? Before your very eyes Jesus Christ was clearly portrayed as crucified.
(Gal 3:1-2)
They interpreted
falsely the myth (or the rite) as the real Roman crucifixion of a seditious, and in this sense they were scandalized and were abandoning Paul.
So also Paul,
if he had in mind a
Roman cruxifixion of Jesus, would be accordingly rightly scandalized like the Galatians. Paul himself would have considered the crucifixion as a
"scandal" and a
"folly" only if he was euhemerizing the Jesus's death just as the his anti-Christian enemies were doing (as effect of their false interpretation of the Christ myth).
What happened, then? The
Judaizers started to share the same strategy of the anti-Christian enemies of Paul,
against Paul in order to win the Paulines:
they euhemerized Jesus's death, also. As reaction, the paulines had to accept,
velim nolim, the historical error of the
"scandal of the cross", i.e., the false belief that Jesus was crucified on the earth by the Romans (or by the Jews), even if they continued still to reject the circumcision and the Torah's observance.
The Judaizers became friends of the anti-Christian enemies of Paul, by sharing their efforts to euhemerize Jesus and represent his death as a "scandal for the Jews". In this way Paul's use of the cross as end of Torah could be neutralized in advance: the cross was really a "scandal" insofar it was
really a Roman crucifixion,
therefore the Torah is still valid,
pace Paul.