The word For at the beginning of verse 17 provides the basis for not losing heart (verse 16). Verse 18 is a parenthetic explanation, and 5.1 also is connected to verse 16 by the same transition word, For.
This slight momentary affliction: Paul sees his sufferings here on earth as temporary in comparison with eternity. Though the Greek noun is singular, that is, affliction, the sense is all of his sufferings as a whole. Revised English Bible says “Our troubles are slight and short-lived.” Other languages may need to use a plural noun to avoid the impression that Paul is talking about one specific incident in which he suffered. Two words are used to emphasize the relative unimportance of the sufferings experienced in this life. The first is an adjective which indicates that they do not last long or are “transitory” (Phillips). And the second is formally a noun but serves to underline their pettiness or insignificance. It gives the idea of “lightness” or lack of “weight.” Some languages may require that a separate sentence be made of this part of the verse: “The troubles we experience are small and they do not last long.”
An eternal weight of glory: the affliction is slight or “light” in contrast with the glory, which is “heavy” or “weighty.” The words weight and glory are closely related in Hebrew, since they are spelled with the same consonants. Paul’s choice of the Greek words weight of glory probably reflects the underlying play on words in Hebrew. In many languages the words weight of glory will have no clear meaning. Good News Translation‘s “a tremendous glory” attempts to capture the sense. Christians are being prepared for glory, which has two characteristics opposed to those mentioned for affliction: it is “eternal” (as contrasted with the “transitory”) and “weighty.” In some languages one may render the last term as “abundance” (Anchor Bible), or in a verbal expression such as “loading us [with everlasting glory]” (Knox).
Beyond all comparison: the comparison is with the short-lived and light-weight suffering of this world. This may have to be made more explicit in the receptor language. That is, one may have to say something like “cannot be compared with the suffering” or “is nothing like the suffering.”
The meaning of this verse may be expressed as follows: “These little troubles are getting us ready for an eternal glory that will make all our troubles seem like nothing” (Contemporary English Version) or “we have our troubles, but they are transitory and unimportant, and all the time they are producing for us a superlative and eternal glory, which will far outweigh all the troubles” (Barclay).
Quoted with permission from Omanson, Roger L. and Ellingworth, Paul. A Handbook on Paul’s Second Letter to the Corinthians. (UBS Handbook Series). New York: UBS, 1993. For this and other handbooks for translators see here .