I know about rightly dividing. However, I would not go so far as to say the same Jews (Peter, James, John) who were filled with the same Holy Spirit as Paul, Cornelius and the rest of the Gentiles are under a different Grace or plan of salvation. Paul even says both Jew and Greek (Gentile).
So I don’t want to take your post incorrectly. Are you saying there are some (kingdom gospel) that are faith+works and others (grace gospel) are faith only? But one Holy Spirit, one Sacrifice?
You need to understand that the believers today as well as the indwelling of the Holy Spirit will be taken from this world at the rapture. The last seven years (the tribulation) will be more along the lines of the old covenant. It WILL be important for people during that seven years to focus on their acts/works because there will be no indwelling or “Christ in them”.
I'm going to take a shot at this because I think it's not coming across correctly.
Is what you're asking whether there are two plans for salvation simultaneously? One for the Gentiles and one for the Jews?
Because that's what it sounds like you're asking.
As I understand it, (and smvoice will probably need to correct it) there is the gospel of the Kingdom, which is for the Jews, in which baptism and works played a role in salvation. It was first offered to the Jews. The Jews rejected it, and then we moved into the times of the Gentiles, the age of grace, where all, Jew and Greek alike, as saved only through faith, without works including baptism.
Once the church is removed from the earth in the rapture, the time of the Gentiles, the age of grace, will be at an end, and then the rules of the kingdom will be in place, by which salvation is determined by how the persons faith works out.
That's my stab at it.