Assurance: How do we know that the gospel is true?

Last week, I wrote about how evidence-based arguments are tools which can only reach probable conclusions, even in the realm of apologetics. A good argument (and Christian apologists have many) can demonstrate a very, very high probability that the God of the Bible exists, but the honest apologist should always admit that his arguments cannot demonstrate the truth of Christianity with absolute, 100 percent certainty. My article last week talked about why this is not a problem, because we are not merely bringing unbelievers to the conclusion of a syllogism, but to a real, active God without whose call no one would believe (John 6:44). But the topic raises other questions for the thoughtful Christian. If evidence-based arguments cannot offer perfect certainty, does that mean the most we can say about the Bible is that it is probably true?

The answer to that question is an emphatic “No.” When I say the Bible is true, I am speaking from a deeper confidence than that which comes from accumulated evidence. Compelling evidence may prompt someone to seriously investigate the claims of Scripture, but once they surrender themselves in faith–once they become a Christian–the real presence of God enters them in the person of the Holy Spirit; and that changes everything. Among many other things, the presence of the Holy Spirit means we can know in a new and different way.

As human beings, we are born with two primary ways of knowing. We know about the external world through our senses, learning things like the color of the grass or the temperature of a summer day. Additionally, we know about our internal condition in a more immediate, direct way. I don’t rely on my senses to know I am angry or happy or in love–awareness of such feelings is simply part of my experience of myself. We build our picture of the world from these two sources of truth: our senses for the outside world, and our immediate self-awareness for what is inside.

For Christians, the arrival of the Holy Spirit as a real presence in our very selves adds a third avenue of knowing. Paul writes, “For you have not received a spirit of slavery leading to fear again, but you have received a spirit of adoption as sons by which we cry out, ‘Abba! Father!’ The Spirit Himself testifies with our spirit that we are children of God” (Romans 8:15-16, cf I John 5:6). This promise suggests a third path to true knowledge, depending on neither our senses nor our self-awareness, but on “testimony” of some sort from the Spirit. But what does that mean? What would it look like? How would this testimony be perceived or known?

Matthew 16:17 offers a helpful indication. After Peter declared that Jesus was “the Christ, the Son of the living God,” Jesus replied, “Blessed are you, Simon Barjona, because flesh and blood did not reveal this to you, but My Father who is in heaven.” Since the Bible does not record any sort of audible testimony from God preceding Peter’s confession, it appears that Jesus was simply referring to a growing and settled conviction in Peter’s mind and heart, fed by what he had observed as a disciple, which Christ knew could only have come from the work of the Father.

It is worth noting that, after this incident, Peter apparently doubted his Lord enough to flee when he was arrested, deny him three times, then collapse into despair with the rest of the disciples after the crucifixion. Plainly, whatever assurance Peter felt could still be shaken. But the fact remains: Jesus said that Peter’s confident testimony was from God. And in the long run, that testimony stood firm. Peter went on to become a leader of the early church, helped spread the gospel across the Mediterranean, and eventually was martyred, still holding fast to the belief he had received as a gift from the Father.

Peter’s story suggests that we will experience the Holy Spirit’s testimony as a conviction which can be shaken and doubted at times, but which ultimately will strengthen and prevail. And, just as Peter’s God-given assurance was fed by his experiences as a disciple, our assurance will grow through observing the evidence of the Spirit’s work in our lives–an increasing love for our brothers and sisters in Christ, an increasing love and desire for Christ himself, and an increasing conformity to his example. The objective evidence of the Holy Spirit’s activity in our lives, along with the never-changing promises of God, form the scaffolding of the Spirit’s proclamation that we are children of God.

If we could only see things as they really are, our restful confidence in the Holy Spirit’s testimony would be unshakeable. But we don’t see things as they are. We still live in this world, where “we see in a mirror dimly” (I Corinthians 13:12). “Faith is the assurance of things hoped for, the conviction of things not seen” (Hebrews 11:1), but we do not yet have perfect faith, so, like Peter, we struggle sometimes to know that we know what we know.

But we can know it. No, we do know it. If you have believed in Jesus for salvation, you have the Holy Spirit within you bearing testimony with your spirit that you are a child of God. In a world where everything can be questioned, that quiet voice is the only one which can promise true certainty, because it comes from the Spirit who alone knows the mind of the Father (I Corinthians 2:11). When you doubt the truth of what you believe, arguments and evidence can help, but real confidence can only come from the testimony of one who knows. Look for the fruit of his work in your life and listen to the promise that he makes. “And the testimony is this, that God has given us eternal life, and this life is in His Son. He who has the Son has the life; he who does not have the Son of God does not have the life. These things I have written to you who believe in the name of the Son of God, so that you may know that you have eternal life” (I John 5:11-13).

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