Speak Out in Faith - Titus 1:13

For there are many unruly and vain talkers and deceivers, ... Whose mouths must be stopped, who subvert whole houses, teaching things which they ought not, for filthy lucre’s sake. One of themselves, even a prophet of their own, said, The Cretians are alway liars, evil beasts, slow bellies [lazy gluttons]. ... this witness is true. Wherefore rebuke them sharply, that they may be sound in the faith; Not giving heed to Jewish fables, and commandments of men, that turn from the truth.

Paul gives an interesting remedy to those blatantly teaching falsehoods: "rebuke them sharply". And what's more interesting is the reason/result: "that they may be sound in the faith." This is very interesting advice, since we are told elsewhere by the Savior that "contention is of the devil." But it occurs to me that it is possible to give a rebuke in love; so that it does not produce contention, as we're told in a later revelation from the Savior:

Reprov[e] ... with sharpness, when moved upon by the Holy Ghost; and then show... forth afterwards an increase of love toward him whom thou hast reproved, lest he esteem thee to be his enemy; (D&C 121:43)

Paul here is preaching sound doctrine. Which is that a solid rebuke, frankly pointing out evil for what it is, actually promotes faith. But it appears that it must be done in love for it to have the desired effect.

Another point that must be considered in this context is the role of the Holy Ghost. We must absolutely follow His dictates. As the above quote states: "when moved upon by the Holy Ghost". There are likely times when it is far better to just keep our mouth shut, or leave, than to start a rebuke or a sermon... It very much depends on us doing and saying what the Lord wants, and not so much the nature and occasion of our speaking out.