How can we know we’re in Jesus’ kingdom, and live in it with his intensity?

In Colossians 1:13 the apostle Paul assures us that God has brought us into the kingdom of the Son he loves. Anyone who is a Christian is part of the kingdom of God—his realm, his world, under his sovereignty. Passages like 1 John 5:13 promise we can know that we have eternal life. No need for false humility ("Well, um, I wouldn't want to be presumptuous or arrogant or claim I'm saved...")

We can and should have confidence. Yet such passages mustn't be isolated or pulled out of context. 1 John 1:6-2:6 insists that we walk was Jesus walked, walking in the light. This means not perfection, but determination and active faith. As we strive to follow him, his Spirit encourages us to live for him. Spiritual fervour (Rom 12:11) is more than a feeling. It's an orientation and a lifestyle. It flows from a relationship with God.

Today I spoke for an hour with a man who stopped going to church, reading the Bible, and living for Christ ten years ago. I'm fairly confident that had he continued in the fellowship and in the Word, he'd still have the excitement of purpose he fondly remembers from his years as a Christian. How sad.

The Bible warns that in old age we can lose passion and desire (Ecc 11:9-12:8). If we're not careful, we can even grow cold in our love for the Lord (Matt 24:21). Intensity and passion for the Lord should be our "normal." And this isn't for new believers or young Christians. It's lifelong. We are like a tree: "They are planted in the house of the Lord... they still bear fruit in old age; they are ever full of sap and green, to declare that the Lord is upright..." (Psalm 92:13-15).