This passage urges those in Corinth who deny Christian resurrection to accept what is true. Now Paul warns all of them not to be deceived by those who don't believe in the resurrection.
He may be quoting a popular phrase of the day when he says "bad company ruins good morals." In so far as it's being used here, that's a sentiment Paul is endorsing.
There are distinct, spiritual dangers to associating with those who are out of sync with God.
