Praise be to Allah the Lord of the Worlds.
Tawheed is a clear Islamic creed, and this is why the testimony of faith was called the Kalima (Word) of Tawheed. Tawheed means affirming the attribute of Oneness to Allah, and by doing so a believing slave affirms that Allah is the one and only God, Lord, and that He, alone, has the Most beautiful Names and Attributes. The Noble Quran has made Tawheed an earmark in the life of man since whoever believes that Allah is the only God, Creator, and Provider will definitely surrender his heart to faith. Allah the Almighty says, "And this Qur’an hath been inspired in me, that I may warn therewith you and whomsoever it may reach. Do ye in sooth bear witness that there are gods beside Allah ? Say: I bear no such witness. Say: He is only One God. Lo! I am innocent of that which ye associate (with Him)."{Al-An`am, 19}.
Divinity is derived from divine, and believing in it affirms that Allah is worthy to be worshiped by His creations; whereas, Lordship is derived from Lord, and believing in it affirms that Allah is the best Disposer of affairs. Oneness of Names and Attributes affirms that Allah is worthy of all perfections indicated by His Beautiful Names and Sublime Attributes.
There are verses in the Quran indicating unity between Allah`s Lordship and Divinity. Allah says in this regard, "Lord of the heavens and the earth and all that is between them! Therefore, worship thou Him and be thou steadfast in His service. Knowest thou one that can be named along with Him ?"{Maryam, 65}. Therefore, whoever believes in the Lordship of Allah affirms His Divinity, and whoever affirms His Divinity affirms His Lordship. Allah says, "There is no God save Him. He quickeneth and giveth death; your Lord and Lord of your forefathers."{Ad-Dukhaan, 8}.
Listing the categories of Tawheed and dividing them according to their meanings is neither a violation of Sharia nor science. Rather, Tawheed could be divided into more than three categories, so we could add: Oneness in Person, Oneness in Attributes, and Oneness in Actions. However, it is wrong to say that the disbelievers believe in the Lordship of Allah. This assumption is invalid as indicated by the aforementioned texts, and none of the prominent scholars has ever separated belief in the Lordship from belief in the Divinity. This is because saying that they are separate will invalidate many sayings. For example, saying that the disbelievers believe in the Lordship although Allah described them as polytheists and disbelievers. What led the proponents of this saying to fall into this doubt is the apparent recognition of some disbelievers that Allah is the Creator. For example, the verse in which Allah says, "And if thou ask them who created them, they will surely say: Allah. How then are they turned away ?"{Az-Zukhruf, 87}.
The scholars of Islamic theology and Quranic exegesis explain the secret behind the answer of the disbelievers in such verses. They say that the disbelievers recognition of Allah`s Oneness is an attempt to evade answering the question because the truth is crystal clear. Although the disbelievers don`t believe this to be true, none can deny that Allah is the Creator, the Provider and the Disposer of all affairs, given the evidence reflected in human beings, heaven and earth. Therefore, Allah has denied their leaving the clear truth by associating partners/deity with Him. Rather, he described them as liars and disbelievers where He said, "Truly God does not guide one who is a liar, a disbeliever."{Az-Zumar, 3}. Al-Baidawi said in his interpretation of this verse: "And verily, if thou shouldst ask them: Who created the heavens and the earth ? they will say: Allah"{ Az-Zumar, 38}: the evidence that none but Allah can be the Creator is so clear that the disbelievers had to accept it: {al-Baidawi, 4/216}.
The Quran invalidates the claim that the disbelievers believe in the Lordship of Allah. On the contrary, it proves the opposite. They have disbelieved in the Lordship by associating partners/deity with Allah. Allah says-via Prophet Yusuf-""O my two companions of the prison! (I ask you): are many lords differing among themselves better, or the One God, Supreme and Irresistible?"{Yousef, 39}, "Nor would he instruct you to take angels and prophets for Lords and patrons. What! would he bid you to unbelief after ye have bowed your will (To God in Islam)?"{Al-Emraan, 80}, and said, "They take their priests and their anchorites to be their lords in derogation of God, and (they take as their Lord) Christ the son of Mary; yet they were commanded to worship but One God: there is no god but He. Praise and glory to Him: (Far is He) from having the partners they associate (with Him)."{At-Tawbah, 31}.
In conclusion, dividing Tawheed into categories for the sakes of educating and clearing its meanings doesn`t violate Sharia. But, dividing it in a way that makes disbelievers look as if they believe in the Lordship of Almighty Allah contradicts what is clearly established in the Noble Quran. This can be more dangerous when employed as a pretext for accusing some Muslims with disbelief based on the excuse that they deny the Lordship. They do this using secondary issues in Islamic Fiqh, such as invocation with the saints and seeking their blessings. This is in addition to other issues within Islamic Fiqh (Jurisprudence), which aims to unite and not divide. And Allah the Almighty knows best.