Tawheed (توحيد) – the Oneness of Allah – is the foundation of Islamic belief. It means affirming that Allah alone is the One true Lord, Creator, and only One worthy of worship, without partners, associates, or equals. All Prophets were sent with the message of Tawheed. The Qur’an and Sunnah emphasize its importance throughout.
Allah says:
وَلَقَدْ بَعَثْنَا فِي كُلِّ أُمَّةٍ رَّسُولًا أَنِ اعْبُدُوا اللَّهَ وَاجْتَنِبُوا الطَّاغُوتَ ۖ
(Surah An-Nahl, 16:36)
Translation: And We certainly sent into every nation a messenger [saying], “Worship Allah and avoid false gods.”
Allah also says:
وَمَا خَلَقْتُ الْجِنَّ وَالْإِنسَ إِلَّا لِيَعْبُدُونِ
(Surah Adh-Dhariyat, 51:56)
Translation: And I did not create the jinn and mankind except to worship Me.
Tawheed is essential for salvation, and Shirk (associating others with Allah) is the greatest sin. Allah says:
إِنَّ اللَّهَ لَا يَغْفِرُ أَنْ يُشْرَكَ بِهِ وَيَغْفِرُ مَا دُونَ ذَٰلِكَ لِمَنْ يَشَاءُ ۚ
(Surah An-Nisa, 4:48)
Translation: Indeed, Allah does not forgive association with Him, but He forgives what is less than that for whom He wills.
Tawheed brings peace and guidance. Allah says:
الَّذِينَ آمَنُوا وَلَمْ يَلْبِسُوا إِيمَانَهُم بِظُلْمٍ أُو۟لَـٰٓئِكَ لَهُمُ ٱلْأَمْنُ وَهُم مُّهْتَدُونَ
(Surah Al-An‘am, 6:82)
Translation: Those who believe and do not mix their belief with injustice (i.e., Shirk) — for them is security, and they are rightly guided.
The first pillar of Islam is the declaration of Tawheed:
لَا إِلٰهَ إِلَّا اللَّهُ
Translation: There is no deity worthy of worship except Allah.
The Prophet Muhammad ﷺ said:
قُولُوا لَا إِلٰهَ إِلَّا اللَّهُ تُفْلِحُوا
(Musnad Ahmad)
Translation: Say “La ilaha illallah” and you will be successful.
He also said:
حَقُّ اللَّهِ عَلَى الْعِبَادِ أَنْ يَعْبُدُوهُ وَلَا يُشْرِكُوا بِهِ شَيْئًا
(Bukhari & Muslim)
Translation: The right of Allah upon His slaves is that they worship Him and do not associate anything with Him.
In another hadith:
مَن مَاتَ وَهُوَ يَعْلَمُ أَنَّهُ لَا إِلٰهَ إِلَّا اللَّهُ دَخَلَ الْجَنَّةَ
(Sahih Muslim)
Translation: Whoever dies knowing that there is no god but Allah will enter Paradise.
In the grave, the first questions will be related to Tawheed:
مَنْ رَبُّكَ؟ مَا دِينُكَ؟ مَنْ نَبِيُّكَ؟
(Sunan Abu Dawood)
Translation: Who is your Lord? What is your religion? Who is your Prophet?
Tawheed frees the soul from worshiping anything besides Allah and leads to sincerity and humility before Him alone. It is the key to acceptance of deeds and the path to salvation.
Allah warns against Shirk and its consequences:
وَلَقَدْ أُوحِيَ إِلَيْكَ وَإِلَى ٱلَّذِينَ مِن قَبْلِكَ لَئِنْ أَشْرَكْتَ لَيَحْبَطَنَّ عَمَلُكَ وَلَتَكُونَنَّ مِنَ ٱلْخَاسِرِينَ
(Surah Az-Zumar, 39:65)
Translation: And it was already revealed to you and to those before you that if you should associate [anything] with Allah, your work would surely become worthless, and you would surely be among the losers.
In conclusion, Tawheed is the essence of Islam. It is the first duty upon every human being and the foundation of all acts of worship. The Qur’an and Sunnah give it the highest priority. Sincere belief in Tawheed leads to salvation, while its rejection leads to eternal loss.