All praise be to Allah, the Lord of the worlds, and truly the good end shall always be for the righteous. Peace and blessings be upon our Prophet Muhammad (peace be upon him) and upon all Prophets, Messengers, and righteous people.
allah (may He be Praised and Exalted) sent His Honorable Messengers to guide people to know Him, to call to Tawhid (belief in the Oneness of allah/ monotheism), and sincere and pure dedication of 'Ibadah (worship) to Allah Alone, as Allah (Exalted be He) says:
And verily, We have sent among every Ummah (community, nation) a Messenger (proclaiming): "Worship Allâh (Alone), and avoid (or keep away from) Tâghût (all false deities i.e. do not worship Tâghût besides Allâh)."
Allah (may He be Praised) explains in this glorious Ayah (Qur'anic verse) that He sent a Messenger for every Ummah (nation based on one creed) to invite them to worship Allah Alone and avoid worshipping Taghut (false gods).
The core of 'Ibadah is Tawhid; and around it always revolved the conflict between the prophets and their Ummahs, as the Mushriks (those associating others with Allah in His Divinity or worship) worshiped Allah (may He be Praised), but also others besides Him. Therefore, Allah sent Messengers to order them to worship Him Alone and abandon the worship of any other than Him, as Allah (Exalted be He) says:
And (remember) when Ibrâhîm (Abraham) said to his father and his people: "Verily, I am innocent of what you worship, Except Him (i.e. I worship none but Allâh Alone) Who did create me; and verily He will guide me."
Allah informs that His Khalil (the close friend of Allah), Ibrahim (Abraham, peace be upon him), declared himself innocent of what his people worshipped, except Allah Alone. This is the meaning of Allah's Saying: Except Him (i.e. I worship none but Allâh Alone) Who did create me This indicates that they were worshipping Allah, but also worshipped others besides Him. Therefore, Ibrahim renounced all the gods they worshipped, except for the One who created him, and that is Allah (Exalted be He). He (Glorified be He) is the only One deserving of worship, because He is the Creator and the Sustainer of all.
The word "created" here means that He created him without modeling on a previous example (i.e. with no precedence), and only One with such power deserves to be worshipped, with none beside Him. Allah (Exalted be He) says:
And We did not send any Messenger before you (O Muhammad ﺻﻠﻰ ﺍﷲ ﻋﻠﻴﻪ ﻭﺳﻠﻢ) but We revealed to him (saying): Lâ ilâha illa Ana [none has the right to be worshipped but I (Allâh)], so worship Me (Alone and none else)."
Allah (Glorified and Exalted be He) says that He revealed to all the Messengers before the Last of the Prophets, Muhammad (peace be upon him), that there is no deity except Him that is worthy of 'Ibadah and He orders them to worship Him Alone.
This shows that all deities that are worshipped other than Allah, whether they are prophets, Awliya' (pious people), idols, trees, Jinn, angels, etc., are all false deities.
This meaning is clarified by Allah's Saying: That is because Allâh — He is the Truth (the only True God of all that exists, Who has no partners or rivals with Him), and what they (the polytheists) invoke besides Him, it is Bâtil (falsehood).
Allah (Glorified and Exalted be He) informs about the Mushriks, when they were called by our Prophet Muhammad (peace be upon him) to testify that there is no deity but Allah, that they said:
"Has he made the âlihah (gods) (all) into One Ilâh (God Allâh). Verily, this is a curious thing!"
Allah (may He be Praised) also says: Truly, when it was said to them: Lâ ilâha illallâh "(none has the right to be worshipped but Allâh)," they puffed themselves up with pride (i.e. denied it). And (they) said: "Are we going to abandon our âlihah (gods) for the sake of a mad poet?"
This shows that they knew that the testimony of Tawhid (La ilaha illa Allah there is no deity but Allah) voids their Shirk (associating others with Allah in His Divinity or worship), as it makes it clear that their deities are false. It inevitably creates the realization that Testifying that there is no deity other than Allah demands dedication of all 'Ibadah to Allah Alone and belief that He (may He be Praised) is the only true God to be worshipped. If this were not so, they would not have been proud and refrained from saying it, because saying it would entail the abolishment of all the other deities worshipped.
Unfortunately, this truth is not so clear to many people, who think that if anyone says there is no deity but Allah that they are a Muslim and that their blood and property are inviolable, even if they dedicate most of their 'Ibadah to other than Allah, such as Du'a' (supplication),