Purpose of Creation
“I did not create the jinns and the humans except to worship Me alone.” (Adh-Dhaariyaat, 51:56)
This is the most explicit verse in the Quran about the purpose of our creation.
Reason for Sending Prophets
“And We sent no Messenger before you but We revealed to him: There is no true god but I; so worship Me alone.” (Al-Anbiyaa’, 21:25)
And verily, We have sent among every Ummah (community, nation) a Messenger (proclaiming): “Worship Allah (Alone), and avoid (or keep away from) Taghut (all false deities, etc. i.e. do not worship Taghut besides Allah).” Then of them were some whom Allah guided and of them were some upon whom the straying was justified. So travel through the land and see what was the end of those who denied (the truth). (16:36)
Reason for Revealing Books
“He sends down the angels with revelation by His command on whosoever of His servants He pleases, saying: Warn people that there is no true god but I, so take Me alone for your protector.” (An-Nahl, 16:2)
Every prophet and messenger received wahy which is the basis of a book. Sometimes it was written down, sometimes not. It is the inspiration they received. Many other books were written down, even though we are most familiar with the 4 famous ones.
Differentiates between Muslim and Kaafir
“It is He Who has created you, but some of you are disbelievers and some of you are believers, and Allah sees what you do.” (At-Taghaabun, 64:2)
Following Tawheed is a Cause of Peace and Contentment in this Life and in the Hereafter.
“Those who believe and whose hearts find comfort in the remembrance of Allah; surely, it is the remembrance of Allah that hearts can find comfort.” (Ar-Ra’d, 13:28)
First Call that we have been Commanded to Do
“O mankind! Worship your Lord Who created you and those before you, that you may guard against evil.” (Al-Baqarah, 2:21)
This is the first commandment that occurs in the Quran.
The Messenger (saw) said to Mu’aadh ibn Jabal, when he (saw) sent him to Yemen: “So let the first thing you call them to, be the testimony that none has the right to be worshipped except Allah.” And in another narration: “…that they worship Allah alone.” (Al-Bukhari and Muslim)
Right of Allah Over Us
The Prophet (saw) said, “O Mu’aadh! Do you know what Allah’s Right upon His slaves is?” I said, “Allah and His Apostle know best.” The Prophet said, “To worship Him (Allah) Alone and to join none in worship with Him (Allah). Do you know what their right upon Him is?” I replied, “Allah and His Apostle know best.” The Prophet said, “Not to punish them (if they do so).” (Related by Al-Bukhari: Vol.9, Bk. 93, No.470)
Cause for Entrance into Paradise
“…..I bear witness that Allah is the only god worthy of worship and that I am His Messenger. No servant shall meet Allah with these two (testimonies) with no doubt regarding them, but he shall enter Paradise.” (Muslim: See Sharh An-Nawawi 1/224)
Forgives All Sins; Prevents Fire of Hell
“A man who never did any good deed, said that if he died, his family should burn him and throw half the ashes of his burnt body in the earth and the other half in the sea, for by Allah, if Allah should get hold of him, He would inflict such punishment on him as He would not inflict on anybody among the people. But Allah ordered the sea to collect what was in it (of his ashes) and similarly ordered the earth to collect what was in it (of his ashes). Then Allah said (to the recreated man), ‘Why did you do so?’ The man replied, ‘For being afraid of You, as You know. ‘So Allah forgave him.” (Al-Bukhari:Vol. 9, Book 93, No. 597)
Abdullaah bin ‘Amr reported that the Messenger of Allah said: “A man will be brought along to the balances on the Day of Resurrection, and there will be brought out for him ninety nine scrolls, every scroll of them stretching when unrolled) as far as an eye can reach, in which are written his sins and his guilty acts, and they will be put in one pan of the Balances. Then a small card will be brought out on which is written the Testimony of Faith: There is no true god except Allah, and Muhammad is His slave and Messenger, which will be put in the other pan and it will outweigh all his wrongdoing.” (Ibn Maajah)
This happened for one person, and it only happened to him. It will not automatically happen for everyone. Something about his shahadah outweighed that of some others.
Dangers of Its Opposite (Shirk)
“Surely, Allah will not forgive that a partner be associated with Him; but He will forgive whatever is short of that to whomsoever He pleases. And whoso associates partners with Allah has indeed devised a very great sin.” (An-Nisaa, 4:48)