"Natural conclusion" is a good choice of words. "Natural", as in "carnal" rather than "spiritual".
"Faith-alone" (note the hyphen) is his own unbiblical construct. Salvation by faith alone without works (which he is not addressing) is a biblical concept.
Friend, please pay attention to the context. In some contexts, the terms can mean different things. It is so in the Word of God and elsewhere in all literature, textbooks, etc.
Natural conculsion" means logical conclusion. But in the context when the natural not subordinated to the spiritual is spoken about, then the natural means carnal.
If that passage is understood with regard to those holy commandments, in which Paul, as he says, delight with his internal man, than the whole Christian teachings about charity are made null and void. What can be more insane!
Consider:
Matthew 22:37–39 — Jesus said unto him, Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind. This is the first and great commandment. And the second is like unto it, Thou shalt love thy neighbour as thyself.
John 13:34–35 — A new commandment I give unto you, That ye love one another; as I have loved you, that ye also love one another.
John 15:1–6 — Every branch in me that beareth not fruit he taketh away… If a man abide not in me, he is cast forth as a branch, and is withered.
John 15:9–10 — Continue ye in my love. If ye keep my commandments, ye shall abide in my love.
John 15:12 — This is my commandment, That ye love one another, as I have loved you.
John 15:14 — Ye are my friends, if ye do whatsoever I command you.
John 15:17 — These things I command you, that ye love one another.
1 John 2:4–6 — He that saith, I know him, and keepeth not his commandments, is a liar… But whoso keepeth his word, in him verily is the love of God perfected.
1 John 3:10–11 — Whosoever doeth not righteousness is not of God, neither he that loveth not his brother. For this is the message that ye heard from the beginning, that we should love one another.
1 John 3:14–15 — He that loveth not his brother abideth in death. Whosoever hateth his brother is a murderer.
1 John 3:18 — Let us not love in word, neither in tongue; but in deed and in truth.
1 John 4:20–21 — If a man say, I love God, and hateth his brother, he is a liar… And this commandment have we from him, That he who loveth God love his brother also.
1 John 5:2–3 — By this we know that we love the children of God, when we love God, and keep his commandments. For this is the love of God, that we keep his commandments.
2 John 1:5–6 — And now I beseech thee… that we love one another. And this is love, that we walk after his commandments.
3 John 1:11 — He that doeth good is of God: but he that doeth evil hath not seen God.
Romans 2:12–13 — For not the hearers of the law are just before God, but the doers of the law shall be justified.
Romans 2:14–15 — The Gentiles, which have not the law, do by nature the things contained in the law… Which shew the work of the law written in their hearts.
Romans 3:31 — Do we then make void the law through faith? God forbid: yea, we establish the law.
Romans 13:8–10 — He that loveth another hath fulfilled the law… Love worketh no ill to his neighbour: therefore love is the fulfilling of the law.
James 1:22–25 — But be ye doers of the word, and not hearers only, deceiving your own selves… a doer of the work, this man shall be blessed in his deed.
James 2:10–11 — Whosoever shall keep the whole law, and yet offend in one point, he is guilty of all.
John 3:19–21 — Every one that doeth evil hateth the light… But he that doeth truth cometh to the light.
John 5:29 — They that have done good, unto the resurrection of life; and they that have done evil, unto the resurrection of damnation.
Matthew 16:27 — For the Son of man shall come in the glory of his Father with his angels; and then he shall reward every man according to his works.
Revelation 14:13 — Blessed are the dead which die in the Lord… and their works do follow them.
Revelation 20:12–13 — And the dead were judged out of those things which were written in the books, according to their works… and they were judged every man according to their works.