What Does the Bible Teach About the Nature of God? Insights from Thomas Aquinas and Divine Simplicity
- Benjamin Michael Mcgreevy
- Jan 23
- 6 min read
The question “What does the Bible teach about the nature of God?” is central to Christian theology and the life of faith. Understanding God is more than an academic exercise; it shapes worship, prayer, moral living, and our very conception of reality. The Bible, considered by Christians to be the inspired Word of God, provides profound insights into who God is, how He interacts with the world, and what it means for humanity to be in relationship with Him.
This exploration becomes even richer when combined with the philosophical and theological reflections of Thomas Aquinas, particularly his arguments in Summa Contra Gentiles. Aquinas provides a rational framework to interpret Scripture and reconcile complex concepts like divine simplicity, omnipotence, and the Trinity. In this blog, we will examine what the Bible teaches about God, explore Aquinas’ contribution to this understanding, and discuss how divine simplicity and the Trinity are consistent with Scripture.
God’s Nature in the Bible: Key Attributes
The Bible describes God through various attributes that reveal His character and essence. These attributes are not separate parts of God but are unified in His singular divine nature.
1.1 God is One
The Old Testament repeatedly affirms the oneness of God. For example:
“Hear, O Israel: The Lord our God, the Lord is one” (Deuteronomy 6:4).
This declaration, known as the Shema, is foundational to biblical monotheism. It emphasizes that God is a single, unified being, not a collection of parts or multiple gods.
1.2 God is Holy
Holiness is a central biblical attribute. The prophet Isaiah records God’s self-revelation:
“Holy, holy, holy is the Lord of hosts; the whole earth is full of his glory” (Isaiah 6:3).
God’s holiness is both moral and ontological, it signifies His perfection, moral purity, and separation from sin. Biblical holiness underscores God’s otherness and transcendence while inviting humanity to participate in His moral goodness.
1.3 God is Sovereign and Almighty
The Bible repeatedly emphasizes God’s sovereignty over creation and history:
“The Lord has established his throne in heaven, and his kingdom rules over all” (Psalm 103:19).
“For by him all things were created… and in him all things hold together” (Colossians 1:16-17).
God’s omnipotence, or all-powerful nature, affirms that nothing exists outside His knowledge, control, or authority.
1.4 God is Love
Scripture also highlights God’s relational nature:
“God is love” (1 John 4:8).
“For God so loved the world, that he gave his only Son…” (John 3:16).
God’s love is not merely an attribute among others; it is intrinsic to His being. It manifests in creation, providence, and ultimately, in the redemptive work of Christ.
1.5 God is Faithful and Unchanging
The Bible repeatedly emphasizes God’s immutability and faithfulness:
“For I the Lord do not change; therefore you, O children of Jacob, are not consumed” (Malachi 3:6).
This unchanging nature guarantees reliability, trustworthiness, and consistency, which is vital for human confidence in God’s promises.
2. Aquinas and the Rational Understanding of God
While Scripture provides revelation, philosophy allows humans to reflect on it rationally. Thomas Aquinas (1225–1274), a medieval theologian and philosopher, made significant contributions to understanding God through reason in works such as Summa Theologica and Summa Contra Gentiles. His writings show how biblical teaching and rational analysis are complementary.
Aquinas’ reflections answer profound questions: How can God be one yet relational as Trinity? How can His attributes coexist without contradiction? How does divine simplicity explain God’s unity?
2.1 Divine Simplicity: God Is Not Composed of Parts
A key concept in Aquinas’ thought is divine simplicity, which he explores extensively in Summa Contra Gentiles (Book I, Chapters 4–8). According to Aquinas, God is simple, meaning:
God has no parts (physical or metaphysical).
His essence is identical to His existence.
Attributes such as goodness, wisdom, and power are not separable qualities but identical to His essence.
This philosophical insight explains biblical statements about God’s oneness. When Scripture declares God as “one” or “holy,” it is not merely describing a function or a quality for He is utterly unified and indivisible.
Divine simplicity also preserves God’s perfection. If God had parts or potentiality, He would be limited or dependent. Aquinas reasons that God, as the first cause and ultimate reality, must be pure act, fully actualized, and without composition.
2.2 God’s Attributes Are Unified
The Bible describes God as loving, holy, omnipotent, and wise. Aquinas’ divine simplicity helps reconcile these multiple attributes: they are not separate in God but are aspects of His unified essence. For example:
God’s power is not different from His goodness; He acts according to His nature.
His wisdom is not separate from His knowledge or being.
Thus, biblical language about God’s attributes reflects the fullness of His one nature rather than compartmentalized traits.
2.3 God as First Cause and Necessary Being
Aquinas also uses philosophical reasoning to support biblical truths. In Summa Contra Gentiles I.13–14, he argues that God is the necessary being—the source of all contingent existence. This aligns with Scripture:
“In the beginning, God created the heavens and the earth” (Genesis 1:1).
God’s necessity explains why everything exists and depends on Him. He is uncaused and self-existent, perfectly independent.
3. The Trinity: Three Persons in One Being
One of the most challenging aspects of understanding God is the Trinity. Scripture reveals that God is one yet exists as three distinct persons: Father, Son, and Holy Spirit.
3.1 Biblical Evidence for the Trinity
Key passages indicate relational distinctions within the Godhead:
Matthew 28:19: “…baptizing them in the name of the Father and of the Son and of the Holy Spirit.”
John 1:1-14: The Word (Logos) is God yet distinct from the Father.
2 Corinthians 13:14: Paul invokes all three persons in blessing.
The Trinity demonstrates that God’s unity is compatible with relationality. The persons are distinct in relation but unified in essence, reflecting divine simplicity.
3.2 Aquinas on the Trinity
Aquinas explains that the three persons share the same divine essence. Their distinction is relational: the Father generates the Son, the Son is begotten, and the Holy Spirit proceeds from both. The Trinity does not imply composition in God but expresses the internal relational realities of one simple being.
This framework allows Christians to maintain monotheism (God is one) while acknowledging the relational richness revealed in Scripture.
4. God’s Transcendence and Immanence
The Bible portrays God as both transcendent and immanent.
Transcendence: God is wholly other than creation (Isaiah 55:8-9).
Immanence: God is present and active within creation (Psalm 139:7-10).
Aquinas provides a rational framework for understanding this tension. God’s transcendence aligns with His simplicity and immutability, meaning He is not subject to change or limitation. His immanence is understood through His sustaining power: God is actively present without compromising His essential unity. In other words, God relates to creation while remaining distinct from it.
5. How This Shapes Worship, Prayer, and Trust
Understanding God’s nature is not purely academic because it shapes our spiritual lives.
5.1 Worship
Recognizing God’s holiness, sovereignty, and simplicity inspires awe and reverence. Worship becomes not only praise for His actions but adoration of His perfect being.
5.2 Prayer
Knowing that God is loving and relational encourages trust in prayer. While God is infinite and transcendent, He is also personal and responsive to our petitions.
5.3 Trust
God’s immutability and faithfulness assure believers that His promises are reliable. Aquinas’ philosophical insights reinforce this by showing that God’s nature is consistent and not contingent on changing circumstances.
6. Integrating Scripture and Philosophy
By integrating biblical revelation and philosophical reasoning, Christians gain a deeper, more coherent understanding of God:
Scripture reveals God’s character, actions, and relational dynamics.
Philosophy, through thinkers like Aquinas, clarifies concepts like divine simplicity, unity, and the Trinity.
Together, they provide a framework for defending the faith, engaging in dialogue with skeptics, and avoiding misunderstandings about God’s nature.
For example, Aquinas’ arguments for divine simplicity and necessity can help explain to those outside the faith why belief in one God is rational, even when Scripture speaks of three persons in the Godhead.
7. Conclusion: The Bible and the Rational Understanding of God
The Bible teaches that God is:
One and indivisible (Deuteronomy 6:4)
Holy and morally perfect (Isaiah 6:3)
Omnipotent and sovereign (Psalm 103:19;
Colossians 1:16-17)
Loving and relational (1 John 4:8; John 3:16)
Faithful and immutable (Malachi 3:6)
Thomas Aquinas’ Summa Contra Gentiles provides philosophical clarity on these biblical truths. Divine simplicity shows that God’s attributes are unified, not separate, and that His essence is identical with His existence. The doctrine of the Trinity, as revealed in Scripture, is compatible with divine simplicity, allowing God to be relational without compromising His unity.
Ultimately, the Bible invites believers to engage both faithfully and rationally with the nature of God. Understanding His attributes, simplicity, and relational complexity enriches worship, prayer, and trust, and provides a solid foundation for dialogue with those exploring the questions of God’s existence, unity, and relational character.
For those seeking to explore the Bible’s teaching on God in a practical, verse-by-verse way, my book Verse by Verse: Genesis 1–11 offers an in-depth guide. Drawing on Scripture, theological reflection, and insights from thinkers like Thomas Aquinas, this devotional unpacks the nature of God, His attributes, and His relational character, helping readers see how divine simplicity, the Trinity, and biblical truths intersect in daily life. Whether you’re a scholar, a student of theology, or someone seeking to deepen your understanding of God’s Word, this book provides a clear, accessible roadmap for engaging Scripture thoughtfully and devotionally.
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