What Is the Trinity?

What Is the Trinity? offers a concise introduction to the Christian doctrine of the Trinity, exploring how Scripture teaches that God is one in essence and three in person—Father, Son, and Holy Spirit.

Dr. R.C. Sproul begins by establishing the Bible’s consistent monotheism, addressing nineteenth-century critical challenges that sought to recast biblical religion as an evolutionary development from simpler forms of belief. He then traces the biblical witness to God’s triune nature, examining key passages in both the Old and New Testaments that reveal the distinction of persons within the one Godhead.

Sproul surveys the major controversies that arose in the early church as theologians labored to articulate what Scripture teaches about God’s nature, including the heresies of Arianism and monophysitism. He explains the church’s historic formulation—one in essence, three in person—and shows why theological precision matters in guarding the faith against distortion. The book concludes by addressing common objections, including the charge that the Trinity is a logical contradiction, demonstrating that the doctrine does not violate the law of non-contradiction.

Part of the Crucial Questions series, this booklet is designed for Christians and thoughtful inquirers seeking a clear and accessible treatment of one of the faith’s foundational doctrines.

Key Themes

• The Bible’s consistent affirmation of monotheism from its opening pages
• The biblical basis for affirming the deity of the Father, Son, and Holy Spirit
• Early church controversies and the development of precise Trinitarian language
• The coherence of the doctrine of the Trinity with the laws of rational thought

Featured Quotes

“Throughout the ages, the church has said that God is one in essence, being, or nature, and three in person.”

“In the beginning was the Word, and the Word was with God, and the Word was God.”