After the Holocaust, Christendom formally rejected this idea of "the law, and the old covenant...dwells in those who love Christ," as you wrote.
For over 50 years, beginning in the Roman Catholic Church and then spreading throughout most mainstream Protestant and Evangelical movements, formal dialogue began between Christianity and Judaism.
By the year 2000, all formal proselytizing efforts of the Jewish people ended in the Catholic Church, and in 2015 the Vatican released the landmark document entitled “The Gifts and the Calling of God are Irrevocable,” stating that the covenant between God and Israel had not, was not, and would never be broken. The document also recognized that while Catholics could not denounce its primary belief that Jesus Christ was the means of salvation of the world, it equally recognized that a personal acceptance of this was obviously not part of the covenant arrangement for the Jews. Therefore it has not been granted to the Church just how the full redemption of Israel is meant to play out in the economy of salvation.
In December of 2015, Judaism responded with the Orthodox Rabbinic Statement on Christianity in which it acknowledge Jesus and Christianity as part of God’s purpose for history and the nations, referred to Jesus as one of the Jewish sages, and even though recognizing that Judaism cannot accept him as the promised Messiah, nevertheless called Christianity a providential partner in God’s plan for world redemption along with the Jews.
The only religious movements that currently refer to the Jewish Covenant being supplanted by the Covenant in Christ are some Fundamentalist Evangelical movements and most groups like the Mormons and Jehovah’s Witnesses. Nominal Christianity generally views supersessionism as anti-Semitic.
The idea of supersessionism has been suggested by some to create a paradox to the Gospel itself. To illustrate, Paul argues that Christians are wild olive branches affixed to the roots of the Olive Tree of Israel. Most suppersessionists claim that Israel is the cursed, fruitless fig tree of Mark 11:12-14.
But if Israel was truly rejected, then Christians are affixed to a rejected root system, with no life to it. But as Paul writes:
If the root is holy, so are the branches...Consider that you do not support the root; the root supports you!--Romans 11:16-18.Obviously the tree and branches were holy and living, even branches that were cut off. The root system could even "support" others. A withered, fruitless system could not do that.
Regardless of any personal views you may have or arguments you may come up with on this, this issue is now generally settled by the mainstream churches of Christendom. It is not my personal view that I came up with. So any further points you have to raise or object to would have to be addressed not to me but to ecclesial authorities of the churches who took 50 years to come to this decision. Especially since the Axis Powers fell without Israel having an army to defeat them and then Israel being restored to its land, and with the Holocaust being a result of Christianity’s theology that the Jews had been abandoned by God (which was at the root of Hitler’s “Final Solution”), Christianity has acquiesced to what it sees as divine providence.
As to the "Second Coming," well, I'm Jewish. For us the term "Messiah" means something like "King" or "President," not "someone who WILL be king" or "president elect." The Messiah in the traditional sense in Judaism was supposed to be a person who was not merely anointed, but someone who actually ruled from a throne and literally was a King in Jerusalem. The person had to be accepted by the Jewish public at large too, because if your subjects don't accept you as king then you aren't a king. And if you die before that happens, your followers can't make up a story and say: "Well, it's supposed to happen when he comes again."
Yeah, right. And the New World of Jehovah's Witnesses has been just around the corner since 1874, uh-huh. Come on! It's 2017 right now, just about to be 2018. If 143 years waiting for this "corner to be passed" is enough time waiting to say we shouldn't trust what the Watchtower says, what does 2000 years say about the Second Coming idea?
Besides, today the idea of the Messiah in Judaism has changed greatly. It isn't likely that anyone in Israel will accept rulership by a monarch. The days of being ruled by kings is long gone. But the idea of humankind finding redemption is still promised and pictured in the figure of what the Messiah represents. Many Jews now see the Messiah as the personification of redemption for all humanity, that time when all peoples evolve beyond selfishness, hatred, war, and move towards peace, love, and work to end suffering in the world and care for their neighbor. It's not so much an individual as it is humanity ruiling over and becoming champion over all of our worst enemies and those things that have plagued us throughout our history.