To forbid from evil is the cause of safety

And when a community among them said: "Why do you preach to a people whom Allâh is about to destroy or to punish with a severe torment?" (The preachers) said: "In order to be free from guilt before your Lord (Allâh), and perhaps they may fear Allâh."

So when they forgot the remindings that had been given to them, We rescued those who forbade evil, but We seized those who did wrong with a severe torment because they used to rebel against Allah's command (disobey Allâh).

al a'raaf 164-165

Safety is in Islam

O you who believe! Take care of your ownselves, If you follow the (right) guidance (and enjoin what is right Islâmic Monotheism and all that Islâm orders one to do) and forbid what is wrong (polytheism, disbelief and all that Islâm has forbidden) no hurt can come to you from those who are in error. The return of you all is to Allâh, then He will inform you about (all) that which you used to do.

Al maeda 105

Comment
To keep forbidding is necessary to create the resistance in oneself from the bad deeds,.

One of the reasons of crse was to not to forbid from sins

On those who disbelieve from among the children of Isra’il , a curse was pronounced by Dawud and ‘Isa, Son of Maryam. All this because they disobeyed and used to cross the limits.

They used not to forbid one another from Al-Munkar (wrong, evil-doing, sins, polytheism, disbelief) which they committed. Vile indeed was what they used to do.

Al maeda 78-79

The responsibility of Ulema (clerics) in present scenario

You will see many of them rushing towards sin and aggression, and (towards) devouring what is unlawful. Evil indeed is what they have been doing.

Why do the Men of Allah and the Men of Knowledge not forbid them from saying what is sinful and devouring what is unlawful? Evil indeed is what they have been working.

Al maeda 62-63

Help in porvoking righteousness

Help each other in righteousness and piety, and do not help each other in sin and aggression. Fear Allah. Surely, Allah is severe at punishment.

Al maeda 2