Therefore whether... — Better, Whether, therefore, it were I or they. Such (see 1 Corinthians 15:3-4) was and is our teaching, such was your belief. It matters not from whom it came, whether from the greatest or least of the Apostles, the gospel was preached, and was accepted by you. These words thus recall the reader from the strong personal feeling shown in the preceding verse to the main argument.
Related Commentaries of 1 Corinthians 15:11
1 Corinthians 15:11
11 Therefore whether it were I or they, so we preach, and so ye believed.