توحيد
Tawḥīd
The oneness of God: one Creator and Sustainer, to whom worship belongs alone.
What it means
From the root w-ḥ-d, “to make one”. Tawhid is the centre of Islam and the meaning of the first half of the shahada, “there is no god but God”. Scholars often describe three aspects: God’s oneness as Lord and Creator, His oneness in worship, and the oneness of His names and attributes, for “there is nothing like Him” (42:11).
The Quran argues for it rather than only asserting it. Had there been gods besides Allah in the heavens and the earth, both would have been ruined (21:22), and each god would have gone off with what he created (23:91).
Often misunderstood as
A bare slogan, or a claim made only to oppose the Trinity.
What the sources say
A hadith in Sahih al-Bukhari says chapter 112, which states God’s oneness, equals a third of the Quran in weight. Islam’s disagreement with Trinitarian doctrine is a disagreement about God’s nature, which Muslims argue from the Quran and from the words of Jesus as they understand them. It is not a denial of the love and honour Muslims hold for him.