‘For we write no other things to you than what you read (anaginosko) or even understand (epignosko), and I hope you will understand (epiginosko) to the end (or ‘completely'), as also you understood (epiginosko) us in part, that we are your glorying, even as you also are ours, in the day of our Lord Jesus.'
(epiginosko can mean - ‘apprehend and acknowledge, receive fully as true, have spiritual knowledge'). He speaks here partly against the charge that what he is like when he is with them is very different from how he is when he writes to them (2 Corinthians 10:1; 2 Corinthians 10:10).
What he has written, he stresses, means exactly what they are reading and apprehending, nothing more nor less. And he hopes that they will eventually understand completely, (or will understand to the end), what they at present apprehend from it partially. That is that Paul is the one in whom they will be glorying in the day of the Lord Jesus because they owe to him their knowledge of the truth, the message of salvation that they received, just as he will be glorying in them because of what the Gospel has accomplished in them. Furthermore they will be glorying because they will recognise that he brought it to them in sincerity and truth (just as he was glorying in 2 Corinthians 1:12 in his own sincerity and genuineness in taking it).
In other words he wants them to know that his written words have no hidden meaning, no duplicity, no hidden agenda. They do not have to read between the lines. What he has written down is precisely what he means, in spite of what some tell them. (This may in fact suggest that his opponents just could not understand his teaching). And that is why they will discover in the day of the Lord Jesus that their glorying will be in Paul and his fellow-workers, because they will recognise in that day, when all truth is revealed, that it was he who brought them the genuine truth sincerely and honestly and openly, and that Paul's glorying will be in them because of what they will prove to be as a result of genuinely hearing his words. Thus they will know then that Paul was a genuine Apostle and that he brought them Apostolic truth, and he will know that they are genuine believers because they responded to that truth.
It need hardly be said that this is the standard by which all who would serve God must constantly test themselves.
‘In the day of our Lord Jesus.' This is the day when Jesus Christ as Lord will Himself finalise His purposes on behalf of His people. In that day, ‘the day of our Lord Jesus Christ', those whom Christ has confirmed to the end will be presented to God blameless and unreproveable (1 Corinthians 1:8). It is the day when the spirit of those who are His will be saved in the ‘day of the Lord Jesus' (1 Corinthians 5:5). It is the day when Paul hopes to have something to glory of ‘in the day of Christ' (Philippians 2:16). It is the day when they will finally be delivered from the power of death (2 Corinthians 1:10). Thus it can be linked with the judgment seat (bema - tribunal) of God as referred to in Romans 14:10-12, or of Christ in 2 Corinthians 5:10, when all that a Christian has done will be tested for its worth, whether it be good or bad, especially his ministry for Christ (1 Corinthians 3:10-15), and everything will be laid bare, even the hidden things of darkness and the counsels of the heart, so that each might receive praise for what he has done which is worthy of such praise (1 Corinthians 4:5).
What glory will be ours when our accomplishments in His name and through His Spirit come out into the light. What shame will be ours when the shoddy work which results from our carelessness and unspirituality sees the light of day, and is despatched into the fire. And we will be the first to cry, ‘burn it up, it is not worthy'.