The Idolators believe in Tawhid Ar-Rububiyyah, which requires them to believe in Tawhid Al-Uluhiyyah

Allah states that the fact that He is One and that He is independent in His creation, control, dominion and guides one to realize that there is no God except Him and that none should be worshipped except Him Alone, with no partner or associate. He tells His Messenger Muhammad ﷺ to say to the idolators who worship others besides Him, even though they admit His Lordship, that He has no partner in Lordship. But despite this they still attributed partners in divinity to Him, and worshipped others besides Him even though they recognized the fact that those whom they worshipped could not create anything, did not own anything, nor do they have any control over anything. However, they still believed that these creatures could bring them closer to Allah,

مَا نَعْبُدُهُمْ إِلاَّ لِيُقَرِّبُونَآ إِلَى اللَّهِ زُلْفَى

Commentary

وَهُوَ يُجِيرُ‌ وَلَا يُجَارُ‌ عَلَيْهِ (And who gives protection and no protection can be given against him - 23:88) The meaning of the verse is that Allah alone can deliver a person from pain and suffering as He wills, but there is none who can save a person from divine punishment. This is true of this world because nobody can stop Allah from rewarding virtuous people nor can anyone protect someone whom He chooses to punish. And the same is true of the Hereafter also. (Qurtubi)