Paul is talking to the Corinthian believers and reminds them what he first brought to them. Seems like some of them did not believe in the resurrection of Christ or that anybody would be resurrected.
He reminds them what he first preached to them.
I make known to you, brethren, the good news that I proclaimed to you, which also ye did receive, in which also ye have stood, 2through which also ye are being saved, in what words I proclaimed good news to you, if ye hold fast, except ye did believe in vain,
"For I delivered to you first, what also I did receive, that Christ died for our sins, according to the Writings, 4and that he was buried, and that he hath risen on the third day, according to the Writings, 5and that he appeared to Cephas," ..Apostles, at 500 and then Paul.
There were some in there midst who were denying the resurrection and this was spreading and corrupting some of their beliefs.
Some were saying:
how say certain among you, that there is no rising again of dead persons?
if there be no rising again of dead persons,
neither hath Christ risen;
if Christ hath not risen, then void [is] our preaching, and void also your faith
And we also are found false witnesses of God, because we did testify of God that He raised up the Christ,
whom He did not raise if then dead persons do not rise
For if dead persons do not rise,
neither hath Christ risen
If Christ hath not risen, vain is your faith, ye are yet in your sin.
whats the advantage to me if the dead do not rise? let us eat and drink, for to-morrow we die!
So if you don't rise from the dead then what the heck, just live for the day, eat drink and be merry. With this belief comes carelessness as some of them were living. They were being led astray by corrupt communication from others.
Be not led astray; evil communications corrupt good manners;
The Corinthians were a new church and seemed to be swayed by certain men who came in and we're teaching different things that what Paul had taught them. It did not seem like there were any leaders in their midst who would put a stop to some of these false teachings. It was to the shame of the Corinthians to let this carry-on.
Paul is once again educating them about death, the resurrection and hopefully straightened them out after this letter. Discipline can be very sobering, It helps one come to their senses and move on. Paul saying this to their shame, it hopefully was enough.
Come back to your senses as you should, and stop sinning! For some of you—I say this to your shame—don't fully know God.