Then he asked me, “So, are you a strict Christian?”

What a fascinating question. Part of me wants to say yes – after all, who wants to be a drifting-along-with-the-flow Christian? But I’m pretty sure that strict is not the best word to express the alternative.

This goes to the heart of a crucial difference between Christianity and Islam. Whichever way you cut it, Islam is basically about following the rules. The friendly Muslim guy on the street will tell you that he certainly doesn’t drink alcohol, and he even makes sure that his trousers are rolled up above his ankles (something in the Hadith, apparently). If you’re talking to a more philosophically-minded Muslim, you’ll learn that Muslim theology pictures Allah as possessing the kind of transcendence that makes it impossible for any kind of “interaction”, properly speaking, to take place across the chasm between him and us. Basically, we’ve just got to what he says and leave it at that.

Christianity, on the other hand, is essentially about being friends with God through Jesus Christ. It’s about being filled with the Spirit, being made one with Christ, and in him enjoying all the blessings of forgiveness and adoption and glory and peace and life and so on that he enjoys and confers on us as God’s incarnate Son. Christianity is a religion of relationship.

So “strict” is a bad way to describe being a full-on Christian as opposed to a half-hearted Christian. Think about other relationships: you wouldn’t refer to yourself as a “strict husband” or a “strict sister”, would you?

But how about “devoted husband” or “committed sister”? That’s better.

Well, yes. And no.

You can be a Christian without going to church in the same sort of way that you can cross the Channel without a boat. Or a plane. Just a wetsuit and a water-proof compass.

In other words, it’s possible, I guess. And occasionally people manage it (normally out of necessity, like Christians locked up in solitary confinement). But why would you want to try? It almost always ends in tears, and there’s a much better way.

What you need is to start rebuilding from the ground up. When you’ve neglected something for so long, the best way forward is to start from scratch. Actually, you’ve forgotten most of what you used to know, and what you can remember is probably wrong anyway.

I call it rusty bike syndrome.

Imagine: you used to have a bike, when you were a kid. Used to ride it all the time. But then one winter you put it away in the shed, and the following spring you never got it out again. There it lay, gathering dust and accumulating rust for years on end. If people asked you whether you had a bike, you’d say, “Yeah, sure I do.” You just never rode it.

Then, one day, you really needed a bike for something, so you went to the shed to fetch the old two-wheeler. But when you finally managed to haul it out, the tyres were flat, the chain was broken, and the handlebars were so rusted that you could hardly turn them. Besides this, it was about 15 inches too small for you.

What are you going to do? A drop of oil here, lick of paint there? Hardly. Get off down to the shop and get one that’s more your size.

Or: open up a Bible and start at the beginning.

The problem with this kind of thinking is that it imagines a sliding scale where God sees things in black and white. Jesus never talked about a sliding scale. He talked about goats and sheep, death and life, condemnation and forgiveness.

Imagine yourself in a boat, anchored towards the north end of Lake Erie. You’re just a few miles upsteam of Niagara Falls, but you’re perfectly safe, because you’re anchored firmly to the lakebed. All around you are swimmers, people in rubber life-rafts, others clinging to pieces of driftwood. There are even a few other boats just like yours, but none of them are tied to anything. They’re all floating steadily north towards the waterfall.

You might be tempted to think that the guys in the big boats are safer than the drifters clinging to bits of wood. But though they might be more comfortable for the time being, they’re no safer in the long run. Everyone who’s not in your boat is drifting in the same direction at pretty much the same speed. The only difference between the fancy big yachts and the flimsy inflatable dinghies will be a slightly bigger splash.