So (Good News Bible‘s “then”) introduces the conclusion of Paul’s argument. One could also phrase this first sentence as “So then, no one should boast….”

Let no one boast is an older English equivalent for “No one should boast.”

For a discussion on boast, see comments on 1.29. This word is used twice as often in 1 and 2 Corinthians as in the rest of the New Testament, and may have been one of the slogans used in controversy in Corinth. Here it describes the misdirected enthusiasm that set followers of Paul, Apollos, and Peter against one another. The Greek is literally “do not boast in men.” Parola Del Signore: La Bibbia in Lingua Corrente brings out the connection between this phrase and the following words: “do not boast of belonging to someone, for everything belongs to you.” The rendering “belonging to someone” seems to fit in better with verse 22 than Good News Bible‘s translation “what human beings can do.” The reference seems to be that of belonging to someone as a follower or disciple. So one may also say “Do not boast of being someone’s follower.”

The final sentence introduces a contrast rather than a logical result. Instead of being proud of being the disciple of some human being, the Corinthian Christians should realize that everything belongs to them. Good News Bible‘s “Actually” is added to express this contrast. The change to a neuter pronoun (all things) is necessary because not only people but things are mentioned in the next verse. In some languages it may be necessary to refer separately to people and things. So one could restructure the final sentence of verse 21 and the first part of verse 22 as “Everyone belongs to you—Paul, Apollos, Peter—and everything is yours—the world, life and death….”

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 .