I do not follow your post, fully.
Romans 15
15:27 It hath pleased them verily; and their debtors they are. For if the Gentiles have been made partakers of their spiritual things, their duty is also to minister unto them in carnal things.
Romans 1
1:11 For I long to see you, that I may impart unto you some spiritual gift, to the end ye may be established;
1:12 That is, that I may be comforted together with you by the mutual faith both of you and me.
1:13 Now I would not have you ignorant, brethren, that oftentimes I purposed to come unto you, (but was let hitherto,) that I might have some fruit among you also, even as among other Gentiles.
1:14 I am debtor both to the Greeks, and to the Barbarians; both to the wise, and to the unwise.
1:15 So, as much as in me is, I am ready to preach the gospel to you that are at Rome also.
1:16 For I am not ashamed of the gospel of Christ: for it is the power of God unto salvation to every one that believeth; to the Jew first, and also to the Greek.
Lol - gotta luv ya.
But ya did it again...
"Close the door; its cold outside - let's go swimming - outside."
Seriously, bro, you can't see the holes in your above?
The spiritual gift (singular) is the Epistle to Romans itself, he says so once more, earlier in chapter 15.
And it is singular - this Epistle of his, to them.
Further, you yourself often assert that those mentioned later in Romans 15 had their own gospel.
And the fact is that "their spiritual things" differ.
While, what the Romans shared with them in that, did not: the gifts of the Spirit he mentions in Romans 12; as in 1 Cor. 12-14; and Eph. 4; etc., did.
All the result of what gift that that both share in common, though?
The New Testament's Spirit Himself.
That can't be right. According to your view, their salvation is yet future.
Fact of the matter?
When all the witness of that shifted over to God's witness thru that to Israel via the Body, that God had turned from Israel for a season "the...saints at Jerusalem" were left "poor."
But you also hold that the Romans were not in the Body. I hold otherwise.
The result being that all these little differences in the understanding of these things, cannot but impact in each of us, as to the overall understanding of all the other "spiritual things" as well, but also continue to reveal that something is amiss in the study approach of one us.
Romans is basically an extended "Bible conference" in written form.
As with Paul's practice, any "Grace Conference" worth its salt will "preach the gospel to you that are at Rome also."
In other words, to all in attendance, lost or saved.
That does not mean said Pastors do so because their attendees are lost, or what have you.
Rather, because that was both Paul's own God-given practice, and his mandate to Pastors, regardless of what their actual subject, or theme for said conference might be.
This is also their practice; every assembly meeting.
At least the more well-rounded and grounded ones.
2 Timothy 4:1 I charge thee therefore before God, and the Lord Jesus Christ, who shall judge the quick and the dead at his appearing and his kingdom; 4:2 Preach the word; be instant in season, out of season; reprove, rebuke, exhort with all longsuffering and doctrine. 4:3 For the time will come when they will not endure sound doctrine; but after their own lusts shall they heap to themselves teachers, having itching ears; 4:4 And they shall turn away their ears from the truth, and shall be turned unto fables. 4:5 But watch thou in all things, endure afflictions, do the work of an evangelist, make full proof of thy ministry.
THAT is Romans - a long, drawn out Bible conference of sorts, the gospel of Christ, included within all those subjects.
ALL ever based on...the gospel of Christ.
Because IT is "the foundation" and "let everyman take heed how he buildeth thereupon" 1 Cor. 3.
EVERY error promoted on here - on prayer, on giving, on works, on no works, on conduct, on this, on that, the other - all those are doctrines - and they all stand or fall on where the particular individual is, in his or her proper understanding of, and obedience to, the gospel of Christ, Rom. 1 and Rom. 15.
Meaning, Paul's intended "fruit" among the Romans is his hoped for his reaching of both the lost, and the saved at Rome.
Towards getting the one saved, and the other established, or fully grounded in the various, minute aspects of the faith.
While his main focus is in laying out the gospel of Christ all the issues he will be addressing those various assemblies at Rome, will be based on.
A very typical, Mid-Acts...practice.
And inn this, as a practice - even in their prayers - it is often obvious that Grace Pastors strive ever to be aware of the impact of their words as they pray within the hearing of others.
What does one often hear in those wonderful prayers?
Romans' dual pattern of both preaching to the lost, and edifying of the saved - that's what.
Both the gospel of Christ AND its' establishment truths.
Yours in him, bro, regardless of our different understandings...
Rom. 5:8
Eph. 4:16.