The four monotheisms compared
Modern philosophical theology distinguishes four broad pictures of one God.
- Trinitarian Christianity: one substance in three eternal persons united in love. God is love not as a property he chose to display but as the eternal life he is.
- Tawḥīd (Sunni Islam): one absolutely simple essence, with the divine attributes (the ṣifāt) eternal but not personally distinct from the essence. The muʿtazila and ashʿari debate within Islam about how to relate the ṣifāt to the essence is famous and unresolved.
- Jewish unitarianism: one person, the Ein Sof of philosophical Judaism. Hesed — covenant love — defines God's actions, with the Davidic covenant and the prophetic tradition pointing forward.
- Deism: one impersonal first cause who set the world in motion and is now disengaged.
All four affirm one God. The question that distinguishes them is eternal personal love. On Trinitarian Christianity, the Father has eternally loved the Son in the Spirit; love is not contingent on creation. On strict unitarianism (Tawḥīd, Jewish unitarianism, Deism), there is no eternal personal love before creation, because love requires a beloved and there was no beloved alongside the solitary divine person.
Richard of St Victor and the *was God always loving?* argument
Richard of St Victor's De Trinitate (c. 1170) makes the philosophical argument crisply. If God is eternally love, love must have an eternal object. A solitary monotheism faces a dilemma: either God needs creation to be loving (which makes creation necessary and threatens divine aseity — God's self-sufficiency), or God was once not loving (which contradicts God is love). The Trinitarian answer is that the Son is the eternal beloved, and the Spirit the eternal love between the Father and the Son. Love is who God is, eternally and self-sufficiently.
Classical Sunni theology has felt this pressure. The ṣifāt debate — whether love is one of God's eternal attributes or a property he displays toward creation — has never produced a consensus settlement comparable to the Trinitarian one. The Ashʿari answer (eternal ṣifāt distinct from the essence) tilts toward something like Trinitarian plurality without naming it. The muʿtazila answer (no real distinction) tilts toward divine simplicity at the cost of the personal language of the Qurʼān. The Trinitarian Christian is not pointing this out to win an argument; he is pointing out that the deepest thing the New Testament says about God — God is love (1 John 4:8) — is metaphysically intelligible only on the Trinitarian picture.
The cross as eternal love spilling out into creation
On the Trinitarian picture, the cross is not God learning to love or deciding to love. It is the eternal love that has always existed between Father and Son spilling out into creation — pursuing a humanity that did not love him in return. John 17:24 — you loved me before the foundation of the world — anchors this. John 3:16 — for God so loved the world that he gave his only Son — is the eternal love operating outward.
This is the deepest theological invitation Christians can offer a Muslim friend. Tawḥīd grounds one God, justice, and command. The Trinity grounds one God, eternal love, and gospel. A Muslim friend longing for assurance that God is for him, not merely over him, has a fuller answer in the Trinity than in tawḥīd. Hold this gently. Most Muslims have never been told that eternal personal love is what Christians mean by Trinity — they have been told it is three gods. Correct the picture, walk through Richard of St Victor's argument, and let the gospel land.
Worked example
The moment
A reflective Muslim friend says, Tawḥīd is the purest doctrine of God. The Trinity is a confused compromise.
What you might say
"I respect tawḥīd more than you might think. It's a powerful doctrine of God's oneness. Let me ask you something though — was Allah always loving? If so, who did he love before he created? Love needs a beloved. Christians believe God has always been love because the Father has always loved the Son in the Spirit. The Trinity isn't a dilution of monotheism; it's the only way God is love makes eternal sense. May I show you what Richard of St Victor wrote about this in 1170?"
Why this works
The answer honors tawḥīd, names the precise philosophical question, and offers a concrete historical theologian to engage rather than a vague claim. It treats the Muslim friend as a serious thinker.
Watch out for
- Treating tawḥīd as straightforwardly inferior. It is a serious doctrine of one God; the Trinity does not negate it but completes it.
- Skipping straight to God is love without the philosophical argument. Without Richard's question, the line lands as sentiment, not theology.
- Forgetting the cross. Comparative monotheism is not finally an exercise in metaphysics; it lands at Calvary, where the eternal love became visible.