There was a time when we Christians felt self-confident enough to make a show of ourselves in public, or at least, when eating together in public. As food was delivered, we'd all screw our eyes up tight, as a member of our party delivered a loud prayer of thanks, for the attention of both God and the other diners (and possibly the kitchen staff). They'd thank him for the food, for the people who prepared it, and for the glorious establishment in which they were consuming it, including of course a brief summary of the four-point gospel for good measure. Other diners would cringe (or, perhaps, make a sudden decision to follow Christ), and an awkward waiter would stand by with the black pepper, but we didn't care.

Today, my experience of the same scenario is different. A group of Christian friends of colleagues attend the same restaurant; as before, the food is brought out from the kitchen. Around the table, hands begin to fidget with forks. One member of the party adjusts his fries and applies a bit of seasoning. But no-one makes a move; everyone instinctively still knows that this might be the point where someone decides they should make a show of themselves. And then, to audible sighs of relief all round, it comes:

The awkward half-grace.

"Well," someone says, with forced confidence. "Thank-you Lord!" The deed is done in the briefest possible way, and the party descends on their meal like a pack of hungry velociraptors. There's been no great act of witness; the waiter is free to distribute the parmesan without a whiff of embarrassment; God has been briefly acknowledged, and, you know, it's better than nothing.

It's not necessarily worse than the old version – where we were often doing one thing (exhibiting gratitude) but really meaning another (bad stealth evangelism). And for many people, both are thankfully inaccurate pictures. Yet I've observed – and taken part – in this strange modern ritual too many times now for it to be a coincidence, and I'm not convinced it's a valuable or progressive step for public Christianity.

I guess the awkward half-grace phenomenon has emerged because we're increasingly aware of the strangeness of our faith. We don't want to look like weirdos; we don't want to draw attention to ourselves. Yet if we reduce saying grace to a moment's discomfort that we hope no-one beyond our table will notice, I worry that we lose something important.

Because for a start, saying thank you makes us thankful. The act of stopping to demonstrate gratitude – both to God and the people who prepared the meal we're about to enjoy – reminds us of the privilege of being able to eat well in a world where so many people go hungry. It engenders a little humility in us instead of allowing us to take what we have for granted.

What's more, saying grace welcomes God into our midst. In the Bible, eating together was such an important rhythm and ritual. When we sit and eat together, we naturally share in a level of intimacy; the dining table is often where strangers become friends. By starting that time with a proper prayer, we recognise God's place in our relationships and lives, and ask him to strengthen both.

Saying grace in public is a little bit uncomfortable, and perhaps it should be. Because in a tiny way, it gives us an opportunity to do something painful because it matters. Saying grace can be a spiritual discipline, an act of obedience which 'faces the fear and does it anyway.' When we worry so much about what strangers will think of us that if forces us to hide our beliefs, we're undermining the freedom our society affords us.

And of course, while it probably shouldn't be our motivation, the act of saying grace can be a moment of witness to those around us. We don't need to present the entire Christian message in some sort of horizontal prayer; it's enough for someone to notice that my faith is central enough to my life that I acknowledge it before eating.

While the latter points will usually be less relevant, the first two are just as applicable in private. I wonder whether by losing the sense of important of grace in public, we'll also start to lose our commitment to it at home.

It's not a big deal in the grand scheme of things. We live under grace – no irony intended – and there are probably bigger issues in all of our lives to sort out. But I do think it's a small sign that our confidence in our faith has waned a little; or perhaps worse, that we've started to become a little too comfortable in a culture of plenty.

So to address a little problem, a modest challenge: why don't we all commit to saying grace in public (and in private) again? Yes it's a little bit awkward and uncomfortable; yes, the people on the next table might snigger. But isn't it worth that to be able to thank God, stay humble, and maybe even plant a seed of intrigue in the mind of the person two tables down?

With apologies to black pepper-wielding waiters everywhere.

Martin Saunders is a Contributing Editor for Christian Today and an author, screenwriter and the Deputy CEO of Youthscape. You can follow him on Twitter: @martinsaunders