The doctrine of the Trinity is an essential of the Christian faith, and it is absolutely necessary to everlasting salvation that one rightly believes in “one God in Trinity and the Trinity in unity” (Athanasian Creed). There are serious implications for denying the plurality of distinct and consubstantial persons in the Godhead. Rejecting the Trinity is tantamount to rejecting God and the gospel, because the one true God is Triune, and the true gospel is grounded in the Trinity. In Defense of the Trinity is an exegetical book on the Tri-personality of God, and it is a concise refutation of Arianism, Oneness theology, and Unitarianism. This book is not an exhaustive study on the multi-personality of God, but it does serve as an evangelistic resource for Christians, and the local church.