Paul is talking about those people with whom we associate or fellowship. We tend to take on the character of the group with which we associate. If we associate with people of bad character, they will succeed in pulling us down to their level.
It is not likely that we will succeed in pulling them up. It is much easier to go down than to go up, especially if those with whom you keep company have no reason to go up, being comfortable with the level at which they are at the time.
John W. Ritenbaugh
What Is Prayer?
This well-known proverb is strategically placed in the Resurrection Chapter. In verse 32, Paul reminds the Greek Corinthians of an example of the perverse, immoral morass that they left compared to the liberating and ennobling calling God has so graciously given them. He then verbally punches them in the nose by telling them the company that they keep is destroying them, meaning they are gradually reabsorbing the attitudes and culture of the surrounding world. He then charges them to wake up to what they stand to lose by being too close to the world—even worldly people who might be fellowshipping with them at services but do not believe in the resurrection of Jesus Christ. Perceiving that some of them are on the verge of losing their salvation, he says, "Shame on you!"
The world's influences are, for the most part, subtle rather than overt. Being familiar to human nature, we find them easy to fall into or return to. What is the problem with the world? Its ruler, Satan, has designed it to lead people to live only for themselves. Therefore, we must fight and resist its attraction, which influences our hearts, because so much is at stake!
John W. Ritenbaugh
The Christian Fight (Part Two)
Self-indulgence leads to excessive striving for yet more worldly pleasure. For those whose chief aim in life is sensual pleasure, there is never enough to satisfy. Self-indulgence can lead to full-blown addiction. Without God's truth of the coming resurrections of mankind, men see no reason to refrain from a life of pleasure and dissipation, ending in death.
Martin G. Collins
Overcoming (Part 8): Self-Indulgence
Other Forerunner Commentary entries containing 1 Corinthians 15:33:
1 John 1:7
1 John 2:15