What are the basic principles of the Gospel that cannot be taken from Christ’s Gospel and make the Gospel not the Gospel? That is a very important question to answer, for, on a very basic level, what people believe in will determine where they will spend eternity. The Gospel of Jesus Christ is bound up in eternal realities that cannot be undone after death if people get the Gospel wrong. Do you believe the Gospel? This work sets down and summarizes the sum and substance of the Gospel of Jesus Christ. What is the sum and substance of the Gospel? How would you summarize it? Is it simply John 3:16? Is it what the penitent thief said to Jesus on the cross? What is the Scriptural data that shows forth enough of the Gospel of Jesus Christ to make it truly Christ’s Gospel? McMahon answers this question by drawing mainly from the book of Isaiah. The Gospel in its sum and substance, or the way God was in Christ reconciling the world to himself, actually contains a great amount of information (the Bible is a very big book). However, in distilling the Gospel down to its essentials, he covers the five principles of the Gospel: Principle 1: God exists. Principle 2: that God is man’s Maker and has made humankind in his image. Principle 3: the bad news that all men have sinned in Adam and are under the curse of God. Principle 4: God has not left all sinners to perish under Adam’s curse, but has given sinners the righteousness of Jesus Christ as a garment to cover them. Principle 5: God calls and draws thirsty sinners to himself through Jesus Christ freely. His five main texts from Isaiah are 40:9, 54:5, 24:5-6, 61:10 and 55:1-3.