http://www.fivedoves.com/letters/jan2022/gino116-2.htm

Romans 16:7 Salute Andronicus and Junia, my kinsmen, and my fellowprisoners, who are of note among the apostles, who also were in Christ before me.

Dear Gino & Doves,

Thank you for writing to me with this question.

While all scripture is given by inspiration of God, and is profitable, I can see how this particular verse could lead to the conclusion that the Gospel of Grace did not originate with Paul and that verses, chapters, books from the Gospel of the Kingdom could be incorporated into our dispensation as if written directly to us also and not just to the Jews only.

If Paul were to say "the Body of Christ" and not just "Christ" in Romans 16:7, then I too could perhaps be persuaded to join in with the various denominations where a mish-mash of the 2 Gospels have been synthesized ("to combine so as to form a new, complex product") in varying degrees.

Hopefully the linked article can clear up your doubts. If not, I have more resources that I can share.

https://forwhatsaiththescriptures.org/category/dispensational-bible-study/were-there-people-in-christ-before-paul/

All the Best,
Mike P.