Have you ever experienced a moment of doubt about your faith – where you know that what you believe is the truth, that you have relationship with God and have received eternal life… but how can you be sure?

I know that I have had these moments, and the author John must have known the same, because he wrote, in 1 John 5:13, “I write these things to you who believe in the Son of God so that you may know that you have eternal life.” Not think or hope, but know. How can we know that we have eternal life? There are three answers to this question.


To put it simply, we know because the Bible tells us so. Revelation 3:20 says, “I stand at the door and knock. If anyone hears my voice and opens the door, I will come in and eat with them, and they with me.” Eating together was, and is, a symbol of friendship. This promise declares God’s desire to have a relationship with us; He will not force this on us, but if we open the door for Him – if we invite Him in – He will come. This is something we can be certain of.

He also promises, “I will be with you always,” and, later, “I will give them eternal life.” This last promise is so exciting! It assures us that Jesus defeated death when He was buried and rose again, so that we, too, are released from the power of death – that our death will not be the end. And what comes after? “No eye has seen, no ear has heard, no mind has conceived what God has prepared for those who love Him.” These are promises we can find in the word of God.


Not our work – it all started long before we were around, at that point in history where Jesus hung on a cross, and three days later

rose from the tomb in which He was buried. Romans 6:23 tells us, “The wages of sin is death, but the gift of God is eternal life in Christ Jesus our Lord.” We have no power here – this gift is given entirely by the power of the only One who could – Jesus Christ. But what really happened in that moment? Scripture tells us, “God made him who had no sin to be sin for us, so that in Him we might become the righteousness of God.” This is the Great Exchange – Jesus Christ, entirely sinless, took our sin onto Himself, suffering and being sacrificed on the cross, in order that His righteousness might be put onto us, who could never achieve it by our own power. What a gift!

It’s magnificent, because it operates in every aspect of our lives – in Him, our past is wiped clean; in the present, we know that Jesus is alive, and we can have relationship with Him – we can know Him. And in the future, we know that if Jesus was buried and rose again, that means we can rise again, too; we will be transformed into the image of Christ, and go to be with Him forever. Wow!


The third Person of the trinity is our third assurance of faith; the word of God, the work of Jesus, and the witness of the Spirit. When we open the door and let God in, it’s the Holy Spirit that comes to live in us. When He lives in us, He starts to make changes – changes that can be seen objectively. Galatians 5:22 lists the fruits of the Spirit – love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, self-control. These changes are not instant; they take time, but as we walk in the Spirit and are obedient to God, they will come.

We also start to see changes in our relationships. Jesus identified the characteristic quality of Christian relation- ships as love – “by this shall all men know that you are my disciples; that you love one another.” This is not a selfish affection; it’s transformative. We start to have compassion for people; to want to make a change, to improve the world. It’s a love that challenges the one who feels it.

But beyond these observable changes, there is a subjective experience – a deep, personal conviction of the truth of God; that we are His children; that we belong to Him. “The Spirit himself testifies with our spirit that we are children on God.” – Romans 8:16.

This is the assurance that we have; the promises of God’s word, the work done by Jesus on the cross, and the love of God given to us in the Holy Spirit.

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