Here is a highly controversial and thought provoking thought from Mark Kinzer. It comes from his book Post-Missionary Messianic Judaism (perhaps the the most fascinating theology book that I have read in the past five years). This is one of his more controversial claims
"In the light of Christian anti-Semitism and supersessionism, the Church’s message of the gospel comes to the Jewish people accompanied by the demand to renounce Jewish identity, and thereby violate the ancestral covenant. From this point onward the apparent Jewish “no” to Yeshua expresses Israel’s passionate “yes” to God – a “yes” which eventually leads many Jews on the way of martyrdom. Jews thus found themselves imitating Yeshua through denying Jesus! If the Church’s actual rejection of Israel did not nullify her standing nor invalidate her spiritual riches, how much more should this be the case with Israel’s apparent rejection of Yeshua!"
So the Jewish rejection of the gospel - once it was tied to a supersessionist framework - was fundamental for preserving Jewish identity (something about which God is very much concerned - or so I think). Thus by rejecting 'Jesus' Jews were - perhaps ironically - showing their fidelity to the God of Jesus.
This is not to suggest, by the way, that Jewish rejection of the gospel when it is not tied to a supersessionist, anti-Semitic framework is necessarily an act of fidelity to the God of Israel.
That said, the rejection of even a non-supersessionist version of the gospel (e.g., Paul's) is still within the providence of God (see Rom 9-11). The (temporary) rejection of Christ by mainstream Judaism is all part of God's purposes.
Sadly supersessionism still rules the roost in Christian theology so is the ongoing Jewish rejection of that 'spin' on the gospel a good thing?