What Difference Does the Trinity Make in Our Assurance?

I’m writing an occasional series about how the doctrine of the Trinity has practical application for our lives. Previous article: What Difference Does the Trinity Make in Temptation?

When a Christian lacks assurance it can manifest in different ways. You might be openly questioning your faith; you might be burdened by legalism, living as if you need to prove yourself to God. Either way, you don’t feel certain that you are saved or accepted in God’s sight as you are right now.

It can be hard to know what to do with either of these problems. How do we pursue assurance?

We need the doctrine of the Trinity. As believers our faith is not in a vague higher power—we trust in the Father, Son, and Holy Spirit as revealed in Scripture. Greg Gilbert’s book Assured (which I reviewed here) has a distinctly Triune emphasis. He helps us to see how each member of the Trinity works to bring us joyful assurance of our salvation.


Gilbert explains that one of the driving sources of assurance is the promises of God. From the time of Adam and Eve, and all throughout the Old Testament, God promises to save the unworthy sinners he has chosen to be his people. The New Testament gives us a fuller revelation of this promise: “God shows his love for us in that while we were still sinners, Christ died for us” (Romans 5:8). So when we hear and trust these promises, our assurance is strengthened. Gilbert writes:

As we’ve already seen, faith is by its very nature a recognition of one’s own spiritual bankruptcy, an admission that we need saving. It’s a mark not of spiritual valor but of spiritual surrender. And God’s inviolable promise is that those who come to his Son—weary, broken, and with imperfect faith—will be saved. (53)

To grasp hold of these promises we must know and trust the character of the promise-giver. We find deeper assurance the more we press into the knowledge of who our Father is.


The previous quote tells us of our Father’s promise to save us, but it also explains the basis of that salvation. Our assurance driven by the gospel of Jesus Christ. We know that we don’t deserve to be recipients of God’s promises. If everything we thought, said, and did for even a single day was written down, could we read over it and feel assured that we’re worthy of God’s acceptance? Surely not! Instead, we cling to grace: “Our confidence that we belong in the presence of God is not self-confidence; it’s Christ-confidence” (30).

We need to keep looking at the person and work of Jesus Christ if we are to trust that we’re saved. While our works can act as a confirming source of assurance (as Gilbert covers later in the book), the true anchor is the work of Jesus on our behalf. He is both the “founder and perfecter of our faith” (Hebrews 12:2).


Yet sometimes the promises and the gospel don’t pierce our minds and hearts. We struggle to actually believe the words of the Bible—indeed, left to our own devices, we cannot believe it. That’s where the Spirit comes in. He applies these truths to our hearts, giving us a felt sense of assurance, not just the objective verdict of salvation. He is our witness.

For all who are led by the Spirit of God are sons of God. For you did not receive the spirit of slavery to fall back into fear, but you have received the Spirit of adoption as sons, by whom we cry, “Abba! Father!” The Spirit himself bears witness with our spirit that we are children of God, and if children, then heirs—heirs of God and fellow heirs with Christ, provided we suffer with him in order that we may also be glorified with him. (Romans 8:14–17)

The Spirit doesn’t give us a steady experience of felt assurance all throughout our lives. Our vision can be clouded by suffering, sin, discouragement, or the everyday burdens of life. So we need to remember that our feelings can’t always be trusted. The objective truths of the promises of God and the gospel of Jesus Christ are our anchors. And the role of the Spirit is to clear the clouds so that we can see those truths clearly.

The more we get to know our Triune God, the deeper our assurance that he will do what he has promised and we will reach fullness of salvation. Surely this should make us celebrate with great joy: “What an incredibly encouraging promise is this, that Father, Son, and Spirit—the entire Triune Godhead—are united in their determination to bring us safely home” (54).

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