Most of the textual differences noted in the UBS and other editions of the Greek text affect the order of words rather than the meaning of the sentence as a whole.

Thinks (Good News Bible‘s “supposes”) leaves open the question whether the person is really “God’s messenger” (Good News Bible) or not.

Spiritual is literally “a spiritual (person).” The same term was used in the plural in 14.1, but probably means “has a spiritual gift” as in Good News Bible.

Acknowledge seems to refer to a mental acceptance or admission that Paul is writing what the Lord has commanded. Other possible translations are “admit” or “agree in his (or, one’s) mind.”

A few manuscripts omit command, giving the meaning “what I am writing to you is from the Lord.” Some manuscripts change command to “commands” in order to agree with “the things I am writing to you.” The most natural way of understanding the phrase command of the Lord is as one particular order; but it may also refer to the whole of the teaching in chapter 14 that Paul has given as an apostle, and therefore with Christ’s authority.

Quoted with permission from Ellingworth, Paul and Hatton, Howard A. A Handbook on Paul’s First Letter to the Corinthians, 2nd edition. (UBS Handbook Series). New York: UBS, 1985/1994. For this and other handbooks for translators see here .