Sorry if I step on feelings of others who hold to a Pre-trib rapture, but that's actually the basis of the doctrine Richard is coming from. Folks like C.R. Stam in the 1940's started the Hyper-Dispensationalist ideas of twin Gospels and only Paul's Epistles as support for the Pre-trib rapture doctrine and Dispensationalism from John Darby in 1830's Britain. Research Hyper-Dispensationalism and you'll understand more of where Richard Burger is coming from.
Understanding Bible prophecy about the lost ten tribes scattered among the Gentiles basically ends those ideas of men's Hyper-Dispensationalism, because God foretold through His prophets that the believing remnants of the lost ten tribes would be gathered WITH the believing Gentiles as one body to Christ Jesus at His second coming (Books of Hosea and Isaiah, where Paul quoted in preaching to Gentiles).
Not only are the orthodox Jews against Bible teaching about the ten lost tribes, but so are many Pre-trib Churches. It's because they try to separate Israelites from the Gentiles with the Dispensationalist doctrines by teaching separate gatherings of Israel and Gentiles by Christ Jesus.
Since you think you can be saved under the Gospel of the Kingdom that Jesus and the 12 taught then go to it. But you will have to keep the Law of Moses.
You, and others, try to take away the liberty that the children of God have in Jesus just as the Jews in the days of Paul were doing. According to Paul the children of God are dead to the Law of Moses and are no longer condemned by not being able to keep them. But you do not want others to believe this because of your Theology of man.
You refuse to believe that Jesus came to the Jews to setup their promised kingdom and the Jews had about 40 years to accept Him as their Messiah and king, and since they still refused, God turned to the Gentile (through Paul) with a gospel of grace.
A person can not be saved by the gospel of the kingdom any longer. They must place their belief, faith, trust, and confidence in the finished work of Jesus on the cross, His shed blood.
I challenge you to read the book of Acts and then show me a scripture where Jesus, Peter and the others preached a gospel that said we are no longer under the Law of Moses and/or we are now saved by the shed blood of Jesus.
You can't do it and you know it so all you are left with is trying to disparage me, to shot the messenger. I say this because that is all you are doing on this forum by taking cheap shots at, not just me but, anyone that doesn‘t believe as you do. But that is okay with me.