In The Name of Allaah, The Most Merciful, The Bestower of Mercy
Among their Shubhah [i.e. doubts portrayed as truth but are falsehood in reality] is the claim that Shirk will not occur in the Ummah of Muhammad [sallal-laahu-alayhi-wasallam] whilst they still testify that there is no deity worthy of worship except Allaah and that Muhammad [sallal-laahu-alayhi-wasallam] is the Messenger of Allaah, and that what has taken place between them [i.e. grave worshippers] and the Awliyaa [i.e. worshipping the graves of the awliyaa] is not tantamount to Shirk.
Response to this Shubhah: Indeed, the Prophet [sallal laahu alayhi wasallam] informed us that certainly the doubts of the Yahood and Nasaaraa will occur in this Ummah, such as the fact that they [i.e. Yahood and Nasaaraa] took their rabbis and monks as lords besides Allaah. [Refer to explanation of this affair in the following links: https://learnaboutislam.co.uk/k-tawheed50-nigeria/ http://www.abukhadeejah.com/ahmad-an-najmees-kitaab-at-tawheed-chapter-5-the-explanation-of-tawheed-and-the-shahaadah-laa-ilaaha-illallaah/ ]
The Prophet [sallal laahu alayhi wasallam] said, ‘’You will certainly follow the ways of those who came before you- hand span by hand span, cubit by cubit, to the extent that if they entered a lizard’s hole, you will also enter it.’’ We [i.e. the Sahaabah] said, ‘O Messenger of Allaah! Is it the Yahood and Nasaaraa?’ He said, ‘Who else?’ ‘’
[Al-Bukhaari’ Number 1397]
Therefore, the Prophet [sallal-laahu-alayhi-wasallam] informed us that some of the people in his Ummah will do what the previous nations did [i.e. misguidance] in religion, customs and the ways in which they govern their affairs. Indeed, shirk occurred in the nations of the past and likewise it has occurred in this Ummah. Indeed, what the Prophet [sallal-laahu-alayhi-wasallam] told us has occurred, for here [i.e. various places in the Muslim lands] are the graves being worshipped besides Allaah with various types of worship. And the Prophet [sallal-laahu-alayhi-wasallam] informed us that the end of time will not come until a part of his Ummah attach themselves to the Mushrikoon and until groups from his Ummah worship idols. [Abu Dawud 4252]
Muhaadaraat Fil Aqeedah Wad-Da’wah’ pages 23-24. Abridged and slightly paraphrased