In chapter one, How To I Know Christianity Is True? Craig says this question can better be answered by briefly surveying some of the most representative thinkers of the past.
In the Medieval era, Augustine and Thomas Aquinas are representative. Augustine saw the universal church as the greatest apologetic that the Scriptures are true. The miracle of the church is greater than the miracle of the Gospel.
Thomas Aquinas distinguished between truths of reason and truths of faith. The existence of God could be proved by the truths of reason but not the Trinity.
In the Enlightenment, John Locke was a theological rationalist who believed in divine revelation but that revelation could not contradict reason. The existence of God is “the most obvious truth that reason discovers,” having an evident “equal to mathematical certainty.”
Henry Dodwell attacked theological rationalism and advocated a subjective apologetic that bypassed reason. The Holy Spirit gives faith and inner light.
In the Twentieth Century, Karl Barth believed that God totally initiates our faith at our encounter with Christ in the Word of God. Rudolf Bultmann believed as stated by Craig that “only a decision to believe wholly apart from evidence will bring one into contact with the existential significance of the gospel.”
Wolfhart Pannenberg believed that if the historical foundation for faith were removed, then Christianity should be abandoned…. Only this evidential approach, in contrast to the subjectivism of modern theology, can establish Christianity’s truth claim.
Alvin Plantinga believed that “according to the model, the central truths of the Gospel are self-authenticating that is to say, they do not get their evidence or warrant by way of being believed on the evidential basis of other propositions.”
In answering the question, “How do I know that Christianity is true?” Craig thinks the question is best answered by distinguishing between knowing Christianity to be true and showing Christianity to be true.
Knowing Christianity to Be True by means of the role of the Holy Spirit and the role of argument and evidence. The believer knows that Christianity is true because the of Holy Spirit who lives in Him (Gal. 3:26; 4:6; Rom. 8:15-16; 1 John 2:20, 27; John 14:16-17, 20). The unbeliever can only know that Christianity is true because of the convicting ministry of the Holy Spirit (John 16:7-11).
The Holy Spirit, however, uses arguments and evidence to minister both to the unbeliever and the believer.
Showing Christianity to Be True is the task of showing that Christianity is true involves the presentation of sound and persuasive arguments for Christian truth claims. Such reasonings can be either deductive or inductive.
I like the way Craig concludes with a danger and an objection. The danger is that we focus to much on apologetics instead of witnessing to the unbeliever. When witnessing share the gospel and if the sinner objects keep focused on the Gospel not winning the argument. Nevertheless, sometimes we must move to showing Christianity is true. In Acts 2, Peter in preaching to the unsaved Jews, referred to fulfilled prophecy, Jesus’ miracles, and especially Jesus’ resurrection.
We know Christianity is true primarily by the self-authenticating witness of God’s Spirit, Craig believes. We show Christianity is true by presenting good arguments that the Holy Spirit uses. Next, Craig shows us what this approach looks like in a real witnessing opportunity:
My friend, I know Christianity is true because God’s Spirit lives in me and assures me that it is true. And you can know it is true, too, because God is knocking at the door of your heart, telling you the same thing. If you’re sincerely seeking God, then God will give you assurance that the gospel is true. Now to try to show you it’s true, I’ll share with you some arguments and evidence that I really find convincing. But should my arguments seem weak and unconvincing to you, that’s my fault, not God’s. It only shows that I’m a poor apologist, not that the gospel is untrue. Whatever you think of my arguments, God still loves you and holds you accountable. I’ll do my best to present good arguments to you. But ultimately you have to deal, not with arguments, but with God himself.