Bambi, "If you can't say somethin' nice, don't say nothin' at all."
But according to the Bible, we must warn others of their errors. Ezekiel 3:17-21 (KJV) plainly says, "Son of man, I have made thee a watchman unto the house of Israel: therefore hear the word at my mouth, and give them warning from me. When I say unto the wicked, 'Thou shalt surely die;' and thou givest him not warning, nor speakest to warn the wicked from his wicked way, to save his life; the same wicked man shall die in his iniquity; but his blood will I require at thine hand. Yet if thou warn the wicked, and he turn not from his wickedness, nor from his wicked way, he shall die in his iniquity; but thou hast delivered thy soul. Again, When a righteous man doth turn from his righteousness, and commit iniquity, and I lay a stumblingblock before him, he shall die: because thou hast not given him warning, he shall die in his sin, and his righteousness which he hath done shall not be remembered; but his blood will I require at thine hand. Nevertheless if thou warn the righteous man, that the righteous sin not, and he doth not sin, he shall surely live, because he is warned; also thou hast delivered thy soul."
And as it says in Proverbs 27:6 (KJV), "Faithful are the wounds of a friend; but the kisses of an enemy are deceitful."
Even Jesus knew it was needful that straying believers require correction. Matthew 18:15 (KJV) says, "Moreover if thy brother shall trespass against thee, go and tell him his fault between thee and him alone: if he shall hear thee, thou hast gained thy brother."
We can see in the following verses that if the erring brother doesn't turn from his wickedness, two or three are to admonish him. Finally, the whole church needs to know and toss out the recalcitrant member.
By the way, Matthew 18:19 and 20 don't mean that Christ shows up at sparsely-attended prayer meetings. The Jews had a law that a case against somebody had to have two or three witnesses. The context of these two verses shows it means that two or three are to witness the issue with the erring brother. "Again I say unto you, That if two of you shall agree on earth as touching any thing that they shall ask, it shall be done for them of my Father which is in heaven. For where two or three are gathered together in my name, there am I in the midst of them."
We can see the context of this statement since Jesus said back in Matthew 18:17 (KJV), "And if he shall neglect to hear them, tell it unto the church: but if he neglect to hear the church, let him be unto thee as a heathen man and a publican."
Here are three examples from Paul which show us that we need to correct those with wrong ideas. Romans 15:14 (KJV) reads, "And I myself also am persuaded of you, my brethren, that ye also are full of goodness, filled with all knowledge, able also to admonish one another."
1 Thessalonians 5:12 (KJV) says, "And we beseech you, brethren, to know them which labour among you, and are over you in the Lord, and admonish you;"
And for those who are expelled from the church, he wrote in 2 Thessalonians 3:15 (KJV), "Yet count him not as an enemy, but admonish him as a brother."
I could include so many other verses stating that correction is what we must do and to do it in a loving way. I'll save those for my next book called You Think You're Going to Heaven? It's not hateful and divisive, as people today say, to warn wicked people and straying believers. Saving people from eternal agony is the most loving deed a person can do for others.