We are told by Paul not only to exhort and encourage one another but to reprove and rebuke one another. We as believers in general need this, and as a body of believers (the church) more so or else the Rot of our sin nature takes over... the folly of pride.
Reprove not a scorner, lest he hate thee: rebuke a wise man, and he will love thee.
Give instruction to a wise man, and he will be yet wiser: teach a just man, and he will increase in learning. (Proverbs 9:8-9)
I charge thee therefore before God, and the Lord Jesus Christ, who shall judge the quick and the dead at his appearing and his kingdom; Preach the word; be instant in season, out of season; reprove, rebuke, exhort with all longsuffering and doctrine. For the time will come when they will not endure sound doctrine; but after their own lusts shall they heap to themselves teachers, having itching ears; And they shall turn away their ears from the truth, and shall be turned unto fables. (2 Timothy 4:1-4)