Assurance was one of the war-cries of the Protestant Reformation. Because we are justified by faith alone, by Christ alone, then assurance is the birthright of every Christian.

But, we need to be careful about how we understand assurance, within the broader matrix of who God is, and what it means to have faith in him. Otherwise, sadly and ironically, a wrong doctrine of assurance could cause us to fall away.

Our understanding of Christian assurance is based on our understandings of the nature of the Bible, and what it means to trust Jesus – to have “faith”. In a previous post, I talked about the significance of understanding the doctrine of predestination in light of the personal nature of God and humanity. God is a person, not an impersonal object. Jesus is a person, not an impersonal object. The Holy Spirit is a person, not an impersonal power (i.e. the force from Star Wars). Likewise, Christians are people, not just impersonal blobs of physical matter.

The relationship between impersonal objects is static, because objects are static. You put two rocks down side by side, and measure the distance between them. That’s it. We know for certain the distance between them. And they don’t do anything any more. They just sit there.

The relationship between people is constantly dynamic, because people are alive – dynamic, active. A good, healthy relationship between people is active in a positive way – it is growing, improving. Stasis is bad for relationships – it indicates stagnation, boredom. If married people say they’re bored with each other, ministers and counsellors get worried, because that means their relationship is deteriorating.

God promises that the Holy Spirit will keep us trusting Jesus. But the nature of that continued trust is active, dynamic – it’s a living trust. That’s because it’s between two people: us, and the Triune God.

Because the nature of Christian faith is personal trust in a person – not the impersonal clarity of mathematics, like the distance between two rocks – Christian assurance also has this personal, living, dynamic element. We trust the Father to keep us trusting Christ the Son by the power of his Holy Spirit.

The way the Holy Spirit keeps us trusting Jesus is through constantly feeding our faith. He feeds our faith positively, by showing how good and attractive Jesus is. Jesus is the Lord who serves (Mark 10:45; John 13:3-4, 13-14), the friend of sinners (Matt 11:19), the one who came to seek and save the lost (Luke 17:7, 10)! Who wouldn’t want to follow him?

The Holy Spirit also feeds our faith in Jesus negatively, by showing how bad it would be to not trust Jesus. He shows how powerless idols are, therefore how stupid idolatry is (e.g. Isaiah 44:9-20; Acts 19:23-41). He also warns us about the consequences of falling away. The most famous warning passages are Hebrews 6:4-8 and Hebrews 10:26-31. But we also need to consider passages like the parable of the sower, the soil and the seeds (Matt 13:3-23; Mark 4:3-23; Luke 8:5-15) and the Apostle Paul’s command to “test ourselves” to see if we are “in the faith” (2 Cor 13:5). These warnings are true, not hypothetical! They truly speak of what happens to those who turn away from Jesus! The Spirit uses them to warn believers: don’t go there!

Christians can sometimes think assurance is like mathematical certainty – the distance between two rocks – rather than personal trust in a mighty saviour. They reason it out like this:

  1. God promises he won’t let his people fall away;
  2. God has made me one of his people – he has brought me to trust Jesus;
  3. Therefore, I can’t fall away.

This may be logically neat, but it is unhealthy for Christian discipleship. This is because it implicitly treats assurance, and faith, and God and humans in terms of mathematics rather than people. It’s the wrong kind of faith, in the wrong kind of God – it’s logic may be neat, but it’s theo-logic is wrong. A false doctrine of assurance could lead to a kind of idolatry: having the wrong kind of faith in the wrong kind of god.

The practical result of the above logic is: the person who believes that stops listening to the warning passages of the Bible. They bounce off him or her, because they say “that can’t happen to me.” So his doctrine of assurance, instead of encouraging them to listen to the Bible and take it seriously, becomes armour against listening to the Bible! And that’s not Christian discipleship – that’s ungodly arrogance…! A faulty theo-logic leads to a faulty view of God which contributes to people falling away.

Instead, if we see faith as a living, personal trust in a living person – our faith in the risen, mighty Lord Jesus – then we will rightly see these warnings as his kindness. He is warning us about what really happens if we stop trusting him. And we believe the warning – we take it seriously, we say “yes, that could happen to me if I’m not careful” – and we don’t fall away.

So, can we be sure that true Christians will never fall away? Yes we can. But it’s because of personal, living nature of faith – we are sure that the personal God will personally keep us personally alive in him. And he’ll keep us true to him through the ordinary means of discipleship. Read the Bible, and when you do, believe what it says, and obey it, respond to it. Pray, and ask God to keep you faithful to him. Go to church, go to a small group Bible study, and open yourself up to being encouraged and rebuked by other Christians.

We need to let the warning passages of the Bible feed our faith in Christ. Otherwise, we’ll end up blunting the sharp edges which God uses to prod us into true faith, true perseverance and true assurance.