Tauhid, the unification of Allâhu ta'âlâ (swt), means that one sees Him in His acts (Tauhid al-Rubbiyah), in our services to Him (Tauhid al-Uluhiyyyah) and in His name and qualities (Tauhid al-Asma wa Sifat) and does not associate with Him any gods. This is the Kalimah of Tauhid,'La Ilahe illa Allah', which Muslims and men must testify to in order to enter into the religion of Islam.
For it contains the rejection of the false gods (La ilahe) and the unifying of ALLLAHs only and alone (illa Allah). If even one mistake in Tauhid appears, i.e. one does not unify ALLLAH (swt) into one of these three categories of Tauhid, but adds something to it, just as the children of Israel or the Christians of ALLLAH (swt) have added something and abused its divine qualities, then one leaves the religion of Islam or does not step into it at all.
Tauhid is not a formula of belonging to any religion, but requires the full implementation of the three categories mentioned and the disavowal of the Schirk and the idolaters, since the Iman at ALLAH (swt) encompasses these aspects.
The idolaters of Mecca, like the idolaters of today, believed in ALLLAH (swt), but they never made it to be Muwahidun because they did not unify ALLLAH (swt) in their worship services to Him. So says ALLAH (swt) the sublime:
"Say (O Muhammad SAW): "Who provides for you from the sky and the earth? Or who owns hearing and sight? And who brings out the living from the dead and brings out the dead from the living? And who disposes the affairs?" They will say: "Allâh." Say: "Will you not then be afraid of Allâh's Punishment (for setting up rivals in worship with Allâh)?" (31) [Yunus, 31]
Tauhid is the foundation of the religion of Islam, which comes from ALLAH (swt) and exists from Adam to the last seal of the prophets Muhammad (saws).
The Messenger of Allah (saws) also defines Islam with the following words:
"Islam is that you worship Allah and you don't make Shirk against Him." (Sahih al-Bukhari and Muslim)
The importance of Tauhid, i.e. to serve ALLAH (swt) alone, is important in that the reason for our existence is precisely this Tauhid. So says ALLAH (swt) the sublime: And I (Allâh) created not the jinn and mankind except whereupon they worship Me (Alone). (56) [Zariyat;56]
The reason for sending the prophets and messengers is also Tauhid! So says ALLAH (swt) the sublime: „And we did not send any Messenger before you but revealed to him: none has the right to be worshipped but I (Allah), so worship me“ (25) [Sura 21 Verse 25]
The reason for the descending of the great books Torah, Bible (which is the unchanged form, which no longer exists today) and the Koran, is also that we are to serve ALLAH (swt) only and alone.
So says ALLAH (swt) the sublime:
Alif-Lâm-Râ. [These letters are one of the miracles of the Qur'ân and none but Allâh (Alone) knows their meanings]. (This is) a Book, the Verses whereof are perfected (in every sphere of knowledge), and then explained in detail from One (Allâh), Who is All-Wise Well-Acquainted (with all things). (1)(Saying) worship none but Allâh. Verily, I (Muhammad SAW) am unto you from Him a warner and a bringer of glad tidings. (2) [Sura Hud Verses 1-2]
Dear brothers and sisters in Islam, if the reason for our existence, the reason for the sending of the prophets and messengers, the reason for the sending down of the books, is Tauhid, what does not let you, O Muslim/a know what Tauhid is?
By order of Islam / Im Auftrag des Islam