Last week someone I consider to be a wise person told me, "If your experience doesn't match your theology, you've got to change your theology."

I've been mulling on that ever since. To my evangelical ears it sounds wrong. Surely theology and doctrine should be immovable? These are the things that keep us anchored in the changing tides of everyday life. After all, Christ built his Church on a rock, not a feeling. If our theology – our thinking about God – is subject to our experience, it becomes an altogether more dangerous game. It's not a terribly comforting thought.

When I made the decision to study academic theology at university (not Bible College), some people in my church (not the one where I presently worship) were horrified. More than once I heard, "You don't want to do that, you might lose your faith." I reasoned that if learning and questioning were threatening to my faith, what possible value could that faith have for me in the long term? What could be the use of a faith unexplored, simply received and accepted?

In fact, in the course of my studies I found my faith broadened and deepened. Yes, it changed dramatically, but it also became far more real and exciting to me. If faith were a thing you could point to, mine bears no resemblance to what it was before. That's not to say I now pour scorn on what was once there, though I genuinely feel much more challenged and fulfilled.

But I'm also less certain. About everything.

I'm privileged to be part of a church that is growing – it's a lively, faithful and moderately diverse evangelical community. But one thing that's notable is that a number of 30-somethings who were there when we first joined have left, not to go to another church, but because they have become disaffected with faith and with Church itself. The answers the Church was offering simply didn't match up to the reality of their life experiences. Given the choice, they went with what made more sense – and who can blame them?

I can't claim this is a national phenomenon or a trend for evangelical Christians in their 30s. If such research exists I haven't seen it. For my part, I have two main thoughts on the issue.

1. I strongly suspect their experience is not unique
2. I wonder if it might actually be a good thing

I'm not criticising the church at which I worship –  if I didn't want to be there or didn't like the leadership I too might be off. Rather, I suspect this is a broader evangelical problem. And, without wishing to be over-simplistic, I think a significant part of that problem is certainty.

There seems to me to be a strong tendency in some church settings to want to offer answers and clarity in an uncertain world. That's a perfectly natural and human thing to do; we have to try to make sense of our faith somehow. But sometimes we take it too far and package up our religion in a box as if it all makes perfect sense. We sand down the rough edges and overlook the things that don't quite fit. We try to tame the Gospel. And we place ourselves in communities of like-minded people so it all becomes one wonderful, gratifying echo-chamber of self-affirmation.

Then we have kids, or we change jobs, or make friends with people from outside that community and experience a change in perspective. The answers we've been given suddenly don't fit the questions. In fact, some of the answers now seem not only inadequate but downright stupid. And so we try to live with it for a while – Sundays in certainty and the rest of the week in turmoil – until the dissonance becomes too much and real life wins. Because there's not enough space in our churches for questions, for wondering.

And so to point two. There's psychological model that says the challenging of one's youthful faith – and even its loss – is a natural stage in the development of a healthy belief system in the long term. Stage Four of James Fowler's faith development theory speaks about the critical examination of and disillusionment with one's former faith as an essential stepping stone to maturity. Ironically, many Christians tend to view those in this stage as "backsliders" whereas in fact they have (in Fowler's stages, anyway) moved forward.

That could sound rather patronising – a kind of "Don't worry, God'll get you in the end". But the reality is that I don't know whether my friends who've walked away from church will ever return. What they find down the road may or may not be a faith in the Christ that I believe in. But I think that their decision to challenge, question and even take a break from religion is actually not only brave but brilliantly honest.

And how exciting it would be if the Church was more willing to learn from them. A fixation on the immovability of doctrine can lead us to reject the experiences of those who question it. And yet the Gospel is fundamentally experiential.

The friend that I quoted at the start of this article also said to me that the Church needs to deal less in exclamation marks and more in question marks. I long for a Christianity that takes our experiences and the reality of this world more seriously, rather than setting up in opposition to them. A Christianity that is willing to live with and live in the questions. A less certain, more honest Christianity.

Anna Drew works in church communications and lives in Kent. Follow her on Twitter @annamdrew.