A good introduction to apologetics, explaining how to reason with unbelievers about God's existence and the authority of the Bible. It's more logical and philosophical than I expected. It would have been easier to follow, and more practical, if it had scripts or example conversations showing how to use the arguments in conversation.
It starts with showing the validity of four principles of epistemology (how we can know anything at all), then moves to two major propositions of apologetics: the existence of God and the authority of the Bible.
It's meant to be a primer, not a comprehensive study of apologetics. As Sproul states, "The task of this book is to set forth, in a brief and nontechnical way, the basic truth claims of Christianity, and to show that at its core Christianity is rational."
The approach: present persuasive arguments for God's existence. Do this in such a way that to deny God's existence would be affirming absurdity. Focus on things that all people must confirm to maintain sanity: the four foundations of knowledge (principles of epistemology). Show that denying any one of them leads to absurdity. Show that following them to their logical end points to a rational Creator (existence of God). Then, establish the Bible's authority. Finally, let the Holy Spirit do his work. Continue the conversation as the other person allows.
Sproul says that establishing God's existence, and thereby the authority of the Bible, takes us 90% of the way in the task of apologetics. The last 10% can be dealt with by careful study of what Scripture says.
Notes
The Apologetic Task
2 macro issues of apologetics: existence of God and authority of the Bible. Even though person and work of Christ is more important, these questions have strategic priority. If Bible is established as carrying divine authority, then its teaching on Christ is confirmed.
Best starting point for apologetics: existence of God. By establishing this first, all other issues of apologetics become easier to defend. Other apologists start by establishing authority of Bible, because that affirms existence of God, reality of creation, deity of Christ. Other apologists argue from history; they prove deity of Christ, then reason back from Jesus to existence of God.
The Four Essential Principles of Knowledge
4 principles of epistemology
Law of Noncontradiction
Causality
Basic reliability of sense perception
Analogical use of language
A paradox is at first a seeming contradiction, but at second glance, a profound truth.
Logical positivism says that only statements that can be verified empirically can be true. That can be defeated by pointing out that that statement itself can't be verified empirically. Atheists use logical positivism to reject God's existence because it can't be verified empirically.
The Case for God's Existence
Reality can't be an illusion. If all reality is an illusion, then nothing exists, including myself. I can't doubt my own existence without proving my own reality; doubt requires a doubter ("I think, therefore I am"). If something (anything) exists, that ultimately demands God's existence (see following points).
A self-creating universe is a contradiction, because for the universe to create itself would require the effect being its own cause, which would require it to be before it was (to be and not be at the same time).
The Law of Cause and Effect doesn't say everything must have a cause; just that every effect must have a cause. The idea of an uncaused being doesn't violate the law.
If something exists now, then something must have always existed. If there was ever absolutely nothing, then there could be nothing now, because nothing can create itself. For something to exist now, logically, there must have been an eternal, self-existent (uncaused, uncreated) being.
There's design in the universe, so there must be a self-existent, eternal something that's responsible for creating the universe. That something must also have intention, which means it must be personal, which leads to the God of the Bible.
To have absolute ethical standards, there must be perfect justice. Because justice is imperfect on earth, there must be perfect justice in the afterlife. That requires a morally perfect judge (above reproach and corruption), which requires omniscience (because judge must have all the facts so judgment is error-free). To ensure judgment is carried out, judge must be omnipotent, so nothing can hinder judgments from being carried out. If moral absolutes exist, then our lives matter, meaning our lives must continue after death, because moral absolutes are given by a perfect judge, who will judge us after life.
The Case for Biblical Authority
Internal authentication (Bible substantiating its own authority)
• Coherency and symmetry
• Consistency over centuries and through multiple authors
• Fulfilled prophecy (e.g., Isaiah, Jeremiah, Ezekiel, Daniel; over 200 specific prophecies about Messiah, fulfilled in Christ)
• Transcendent majesty of scope
• Inner ring of truth (our consciences agree with it, and it accurately describes life as we experience it)
External authentication: findings of historians and archaeologists (Bible contains many names, places, events that have been externally verified), including eyewitness verification of miracles recorded in Bible.
Authors of Bible assume or claim that their words are inspired by God.
Christians believe the Bible is inspired by God because Jesus said so. This isn't circular logic, because the premise is that narratives of Bible are reliable historical documents, which can be shown by external sources.
First, show biblical record is historically reliable. Then, move to biblical writers' description of Jesus' flawless character. Then, judge his claims of prophecy to be reliable because his character is reliable (attested by historically reliable biblical accounts). If his teaching is accurate, we should accept his teaching on Scripture (that it's the verbally inspired Word of God).
When talking to an unbeliever, establish reliability of biblical record, then affirm Jesus' character from what Bible says about him, then ask, "What did Jesus teach about the writings of Scripture?"
If a Christian claims faith in Jesus but denies that Bible is reliable, their faith is empty. Ask on what rational foundation they base their faith. Also ask, "What is the Lord of the church's authoritative teaching about the nature of Scripture?" Jesus spoke about writings of OT prophets. He said they were words of God. He said his own words were true. If his teachings about Scripture were false, he'd be a false teacher. If he was wrong about anything he taught, why would we exalt him as prophet, let alone Son of God?
Remember that no amount of evidence will convince an unbeliever without the Holy Spirit working in their heart.