Why a sermon series on the doctrine of assurance?

Luther as Professor, 1529 (oil on panel) by Cranach, Lucas, the Elder (1472-1553)

1527, Martin Luther wrote, “For more than a week I was close to the gates of death and hell. I trembled in all my members. Christ was wholly lost. I was shaken by desperation and blasphemy of God.” 

If you know your Reformation history, you know that 1527 is 10 years after Luther’s nailing of the 95 Theses on the Wittenburg Door. This is about a decade after Luther’s glorious discovery of justification by faith alone through the imputed righteousness of Christ.

In other words, Luther’s despair came after he was an established Christian. In that dark season, Luther’s battle was for assurance. Questions about his standing with God haunted his weary conscience. Am I an imposter? Am I really reconciled to God? Is my faith enough?

The questions he wrestled with (or the questions that wrestled him) are questions everyone asks at some point. They are eternal questions with eternal consequences. They are questions one must not answer wrongly. When a person thinks they’re right with God when they’re not it’s an eternal disaster. When a person thinks they’re not right with God, when they are, they miss out on God’s blessed gospel gift of assurance.

The doctrine of assurance is critical for the church. Here are three reasons why we need to spend time thinking about this:

First, false assurance runs rampant.

This is in part because of the reality that we in American swim in an ocean of cultural Christianity. I’ve spoken to many people who associate Christianity will good character, high moral values, and conservative politics. 

These are people who are convinced they are Christians, convinced they will be able to stand before God on the Day of Judgment, and that because of something they’ve done, they will be welcomed into heaven when they die.

Ligonier Ministries does a “State of Theology” survey every two years, surveying masses of professing Christians to see what they believe about crucial doctrines. It’s a good way to take the pulse of the modern evangelical church. I looked through the survey mainly looking to see what it revealed about how much these people understand the gospel. Here’s what I found:

As related to God, 51% of evangelicals believe “God accepts the worship of all religions, including Christianity, Judiasm, and Islam.” Right off the bat we see more than half do not believe in a holy God who determines who can come to him and how. The exclusivity of Christ is discarded and the Holy God we encounter in Scripture is replaced with something more palatable for modern sensibilities .

As related to Christ, 78% of evangelicals think, “Jesus is the first and greatest being created by God.” Almost 80% of professing Christians have embraced some form of the ancient Arian heresy, and have more in common with modern Jehovah’s Witnesses than actual orthodox Christianity. They don’t think Jesus is divine and therefore adopt a human Christ who cannot save.

52% of evangelicals believe that people are naturally good, even though they may sin a little, representing a radical departure of the Bible’s teaching about man’s sinful condition. 

So we see the majority of professing believers have a God that’s not holy, a Christ that’s not divine, and a humanity that’s not sinful. It’s no wonder so many people are falsely assured of salvation. Salvation is meaningless without a right understanding of God, of sin, and of Christ. 

In Matthew 7:21-23 Jesus speaks of people who are being cast out from his presence into judgement who claimed to know him as Lord, to speak on his behalf, to cast out demons in his name, and to do many mighty works for him. Their awakening in hell will be the most surprising moment of their lives. 

I write this in deep sadness. It grieves me to think of the multitudes who are happily embracing a false gospel that cannot save them. But it strengthens my resolve to do all I can to clarify the gospel in my church. 

Second, doubt is an issue for true believers.

It’s crucial to say this out loud: real believers sometimes have doubt. We find doubt in the Psalms and doubt in the gospels, even among people who trust God. It is not God’s desire to keep his children doubting his love for them, but because of our weakness and sin, we are prone to fall into doubt. 

Many of us are like the father of the demon-possessed child in Mark 9, if we’re honest. When Jesus said, “All things are possible for one who believes,” the man replied, “I believe; help my unbelief.”

This is why studying assurance is so practical. Who among us hasn’t said or felt the inner tension of that statement: “I believe; help my unbelief!” As not-yet-glorified Christians, we find ourselves to be wavering between belief and unbelief, faith and doubt, assurance and uncertainty. And much of our disobedience and despair comes from the lack of assurance of God’s love for us. 

The doctrine of assurance is an intersection between abstract theological ideas and street-level, everyday application. It’s intensely practical, because there’s nothing more practical than knowing for sure your status before God. If you have certainty there, it changes everything. You cannot know the height and depth and breadth and width of God’s love for you without it affecting your prayer life, your obedience, your attitude in suffering, your desire for his Word, your zeal in evangelism, your eagerness to serve — and the list goes on. Behind so many of our problems is the poisonous belief that God doesn’t really love us that much.

The presence of doubt and despair is traceable back to a certain view of God, salvation, and Christian living. So speaking of assurance helps us deal with all these realities.

Third, God desires that you know for sure.

Cardinal Robert Bellarmine, Pope Clement VIII’s personal theologian, said during the outbreak of the Reformation: “The greatest of all Protestant heresies is assurance.” 

But listen to the Scriptures: 1 John 5:13I write these things to you who believe in the same of the Son of God that you may know that you have eternal life.”

Hebrews 10:22Let us draw near with a true heart in full assurance of faith, with our hearts sprinkled clean from an evil conscience and our bodies washed with pure water.” 

Or think of Paul. Paul knew for sure: 2 Timothy 1:12But I am not ashamed, for I know whom I have believed.”

This is God’s heart for his children. He wants them to be utterly certain of his care. Jesus went to great lengths to make this clear in John 10:

  • Verse 10-11: “I came that they may have life and have it abundantly. I am the good shepherd. The good shepherd lays down his life for the sheep.” 
  • Verse 14-15I am the good shepherd. I know my own and my own know me, just as the Father knows me and I know the Father; and I lay down my life for the sheep.” 
  • Verse 27-28My sheep hear my voice, and I know them, and they follow me. I give them eternal life, and they will never perish, and no one will snatch them out of my hand. My Father, who has given them to me, is greater than all, and no one is able to snatch them out of the Father’s hand.”

This is God’s desire for them. That they might know his love and feel secure. We are not to be motivated by the uncertainty of fear, but by the security of love. We are not in a family where the father motivates his children by threatening to abandon them if they fail, but by saying he’ll love and care for them no matter what.

Have you ever been rappelling? You get strapped up, the harness fitting uncomfortably snug all over your body, and there’s that moment when you have to learn backwards off the edge of some sheer cliff. 

That’s the scariest part of rappelling — when you’re not sure if the rope will hold all of your weight. If you’re not confident it will hold you, you won’t lean back. I’ve seen people watch others rappel, get strapped in themselves, go up to the ledge, and absolutely refuse to lean back. They couldn’t trust the rope with all their weight. And so they didn’t move.

If you don’t trust your Savior, fully and completely, there are going to be limits to your obedience. Do you trust Jesus with the full weight of your eternity? Do you trust him with your life? If you do not, there will be certain risks you will not take. You will never lay down your life until you trust that Jesus will raise it up again on the last Day.

God wants you to be sure and his love for you and your perfect security, and then lay your life down in risk-taking, self-sacrificing obedience.

Christ, Our Hope

Luther discovered justification by faith in 1517, but 1527 was one of the darkest years of his life.  It was also the year Martin Luther composed the hymn, “A Mighty Fortress is Our God.” It was his anthem to ward off the devil and remember the greatness of his salvation. 

Think of the words in the 2nd verse: 

Did we in our own strength confide, our striving would be losing, 

were not the right Man on our side, The Man of God’s own choosing: 

Dost ask who that may be? Christ Jesus it is he; 

Lord Sabaoth his name, from Age to Age the Same, 

And he must win the battle.

Luther saw that we are weak sinners, who cannot strive to save themselves, but that God has appointed a man — who is also God — to be the Savior of everyone who trusts in him. He is our Mighty Fortress. Here is a great statement to start a series on assurance: at the bottom of it all, the grounds of assurance is Jesus Christ. 


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