But: here, as in verse 21, this conjunction is not so much a marker of contrast as an indication of a change in subject. It is represented in many versions by the beginning of a new paragraph. So it may not need to be represented in any other way.
The first part of this verse contains implicit information that may be made explicit in translation: “But I call God to witness against me if I am not telling you the truth.” The Greek is literally “to witness upon my soul [or, life].” The meaning is that Paul calls upon God to punish him if Paul has spoken a lie. It may therefore be better in some languages to translate “May God discipline me if I am not telling the truth” or “If I am lying, may God punish me.”
It was to spare you: the meaning is not “to save your lives” but rather “to avoid causing you further pain” (see 2.1-2). So it may be preferable in some languages to say something like “I refused to return to Corinth because I did not want to cause you any more suffering” or “the reason I did not go to Corinth again was that I did not want to harm you further.”
Coming to Corinth: the use of the verb “come” indicates the point of view of the readers. Good News Translation has “go”—from the point of view of the writer. Either may be an acceptable translation, depending on the normal usage in the receptor language in such a situation. Apparently Paul did go to Corinth before he went to Macedonia; but after his trip to Macedonia, he did not return to Corinth as he had told them he would (see comments on 1.17). Though Revised Standard Version and Good News Translation are literal translations of the Greek, they give the wrong impression by implying that Paul did not go at all to Corinth. The meaning is that he did not return to Corinth after his first stop there while on his way to Macedonia. New Revised Standard Version as well as New Jerusalem Bible and Barrett add the word “again” (“It was to spare you that I did not come again to Corinth”) to indicate that he did indeed go there once. New International Version and Bible en français courant use the verb “return,” while Contemporary English Version has the verbal expression “stayed away from.” Moffatt indicates both the idea of restraint and the information that it would have been a return visit when he says “refrained from revisiting.”
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 .