Jesus addressed this topic in Revelation 3:15-20. He told the people of Laodicea that they were neither hot nor cold, but lukewarm. Had they been hot, He could have cooled them off. Had they been cold, He could have warmed them up. But because they were lukewarm there was nothing He could do for them. To be lukewarm is to live as though you don't need the Savior in your life. It is to adopt the attitude, 'I have need of nothing.' Jesus' solution was, 'Be zealous and repent.'
The problem with the people of Laodicea was that they were prosperous and materially wealthy. Perhaps they had ignored Paul's warning not to trust in uncertain riches but in the living God (1 Timothy 6:17). Their material wealth was preventing them from perceiving their spiritual poverty. This is a common phenomenom in the US and other prosperous western societies.
Jesus said that He came, not to save the righteous, but to call sinners to repentance. What He was saying was that the only people He could help were those who recognized they had needs that only He could supply. The lukewarm fail to recognize their spiritual needs.