In Corinth, the believers struggled with divisions and jealousy among each other. Paul tells them that those things are evidence of a lack of spiritual maturity. There is a call in the Christian life to grow up and mature into our faith, but sometimes our own pride and self-centeredness can stunt that growth.
"But I, brothers, could not address you as spiritual people, but as people of the flesh, as infants in Christ. I fed you with milk, not solid food, for you were not ready for it. And even now you are not yet ready, for you are still of the flesh." 1 Corinthians 3:1-3