Why did Zhou kings use the idea of the Mandate of Heaven

Answer:
To persuade their people to believe that the gods favored their rule
Explanation:
To justify their rebellion against the Shang, the Zhou promoted the idea of the Mandate of Heaven, or the divine right to rule. The cruelty of the last Shang king, they declared, had so outraged the gods that they had sent ruin on him. The gods then passed the Mandate of Heaven to the Zhou, who “treated the multitudes of the people well.”