How does one protect themselves from the affliction and punishment that may befall both the righteous and the unrighteous, knowing that mercy is for the righteous if Allah wills to punish and test a society?

The optimal way to be safe from affliction is through righteousness and piety, and by acting upon what Allah has obligated in reforming the conditions of the Ummah by inviting them to good and clarifying the truth, enjoining good and forbidding evil, and striving against them in the way of Allah. Were it not for this, the earth would be corrupted, as Allah Almighty said: “And if Allah had not repelled [some] people by means of others, the earth would have been corrupted, but Allah is the possessor of favor over the worlds.” (Al-Baqarah: 251). Also: “So when they forgot that by which they had been reminded, We saved those who forbade evil and seized those who wronged with a wretched punishment because they were defiantly disobedient.” (Al-A'raf: 165). And: “So why were there not among the generations before you those of enduring capability forbidding corruption in the earth - except a few of those We saved from among them? But those who wronged pursued what luxury they were given therein, and they were criminals. And your Lord would not have destroyed the cities unjustly while their people were reformers.” (Hud: 116-117). And the Prophet, peace and blessings be upon him, said: “The example of the one who stands by Allah’s limits and the one who falls into them is like a group of people who drew lots for a ship. Some got its upper part, and others its lower part. When those in the lower part wanted water, they would pass by those above them. They said: ‘If we were to make a hole in our part, we would not harm those above us.’ If they leave them to what they intended, they will all perish. But if they restrain them, they will all be saved.” And the Prophet, peace and blessings be upon him, said: “By the One in Whose Hand is my soul, you must enjoin good and forbid evil, or Allah is about to send a punishment upon you from Him, then you will supplicate to Him, but your supplication will not be answered.”