One of the aspects of Tawhid (God’s unity) is unity in divinity. what does it mean?

Most of the polytheists were agreed on the unity in creation. They were disagreed with monotheists on unity in divinity. At the time of His highness Abraham (a.s.) polytheists believed in one God but they thought in error that stars were the lord of the universe. According to the Holy Quran, His highness Abraham had a discussion with them about this matter, i.e. divinity of the heavenly bodies (the moon, the sun and the stars). (1)

At the time of His highness Joseph (a.s.) who lived after His highness Abraham (a.s.), polytheists did not believe in unity in divinity, too. They thought that after creating the universe God has left the management of it to another one. Therefore His highness Joseph (a.s.) has emphasized on the unity in divinity and said that:

O [my] two companions of prison, are separate lords better or Allah, the One, the Prevailing? (2)

The explanation of unity in divinity is that the management of the universe is not separated from the creation of it and in fact it’s management is it’s creation. Since the creator of the universe and the human is One so the managers of them will be One because there is a direct connection between the management and the creation of the universe. Therefore where God calls Himself the creator of all things, calls Himself the manager of them too and says that:

It is Allah who erected the heavens without pillars that you [can] see; then He established Himself above the Throne and made subject the sun and the moon, each running [its course] for a specified term. He arranges [each] matter; He details the signs that you may, of the meeting with your Lord, be certain. (3) (4)

1. Refer to the Holy Quran, Surah 6:76-78.
2. Quarn, Surah 12:39.
3. Quran, Surah 13:2.
4. Features of the Beliefs of Shia, p.58.