You know it has been said by them of old
It is easier to catch flies with honey.
So only preach the sweet things and esp. to professing believers because you do not want to cause them any fear of God or diminish their comfort, no keep them at ease in zion and speak only peaceful things like Peter did when he spoke in the churches:
2 Peter 2:22
For if God did not spare the angels who sinned, but cast them down to hell and delivered them into chains of darkness, to be reserved for judgment; 5 and did not spare the ancient world, but saved Noah, one of eight people, a preacher of righteousness, bringing in the flood on the world of the ungodly; 6 and turning the cities of Sodom and Gomorrah into ashes, condemned them to destruction, making them an example to those who afterward would live ungodly; 7 and delivered righteous Lot, who was oppressed by the filthy conduct of the wicked 8(for that righteous man, dwelling among them, tormented his righteous soul from day to day by seeing and hearing their lawless deeds) — 9 then the Lord knows how to deliver the godly out of temptations and to reserve the unjust under punishment for the day of judgment, 10 and especially those who walk according to the flesh in the lust of uncleanness and despise authority. They are presumptuous, self-willed. They are not afraid to speak evil of dignitaries, 11 whereas angels, who are greater in power and might, do not bring a reviling accusation against them before the Lord.
12 But these, like natural brute beasts made to be caught and destroyed, speak evil of the things they do not understand, and will utterly perish in their own corruption, 13 and will receive the wages of unrighteousness, as those who count it pleasure to carouse in the daytime. They are spots and blemishes, carousing in their own deceptions while they feast with you, 14 having eyes full of adultery and that cannot cease from sin, enticing unstable souls. They have a heart trained in covetous practices, and are accursed children. 15 They have forsaken the right way and gone astray, following the way of Balaam the son of Beor, who loved the wages of unrighteousness; 16 but he was rebuked for his iniquity: a dumb donkey speaking with a man's voice restrained the madness of the prophet.
17 These are wells without water, clouds carried by a tempest, for whom is reserved the blackness of darkness forever.
18 For when they speak great swelling words of emptiness, they allure through the lusts of the flesh, through lewdness, the ones who have actually escaped from those who live in error. 19 While they promise them liberty, they themselves are slaves of corruption; for by whom a person is overcome, by him also he is brought into bondage. 20 For if, after they have escaped the pollutions of the world through the knowledge of the Lord and Savior Jesus Christ, they are again entangled in them and overcome, the latter end is worse for them than the beginning. 21 For it would have been better for them not to have known the way of righteousness, than having known it, to turn from the holy commandment delivered to them. 22 But it has happened to them according to the true proverb: "A dog returns to his own vomit," and, "a sow, having washed, to her wallowing in the mire." NKJV
What you might do is read them these verses below and ask them if they were a shepherd would they ignore this or warn the people ?
Ezek 33:7-9
8 When I say to the wicked, 'O wicked man, you shall surely die!' and you do not speak to warn the wicked from his way, that wicked man shall die in his iniquity; but his blood I will require at your hand. 9 Nevertheless if you warn the wicked to turn from his way, and he does not turn from his way, he shall die in his iniquity; but you have delivered your soul. NKJV
Ezek 34:7 'Therefore, you shepherds, hear the word of the LORD: 8 "As I live," says the Lord GOD, "surely because My flock became a prey, and My flock became food for every beast of the field, because there was no shepherd, nor did My shepherds search for My flock, but the shepherds fed themselves and did not feed My flock" — 9 therefore, O shepherds, hear the word of the LORD! 10 Thus says the Lord GOD: "Behold, I am against the shepherds, and I will require My flock at their hand; I will cause them to cease feeding the sheep, and the shepherds shall feed themselves no more; for I will deliver My flock from their mouths, that they may no longer be food for them." NKJV