Of all the slurs aimed at Christians by atheists, the idea that we're just 'the people who hear voices' is one of the most painful. The thought that religion can simply be conflated with mental illness is offensive for sure, but while faith is a perfectly sane pursuit, even the most devout among us are sometimes uncertain whether we actually heard from God...or made him up in our heads. Doubt is a central part of faith after all, and the question of whether we discerned or understood God's voice is often the main reason that those doubts present themselves.

A key reason for this is that there's no single way in which all Christians agree that God speaks. For some, God's voice comes through a straight reading of Scripture (although many would argue that's all open to interpretation); for others, it's about a sense of guiding within our own feelings. Still other people rely on the guidance of leaders and 'prophets' – the direction and wisdom of God presented through the words and teaching of others. And perhaps for most of us, there's a bit of truth in all of the above; God can and does speak through all of these mechanisms and plenty more: nature, art, prophetic action, the wisdom of great teachers and writers from the past. Given that he spoke through an ass in the Bible, God doesn't seem to be restricted in his use of communication media.

There is one way in which God reportedly speaks however, which feels a little more divisive and even controversial. We're perhaps uncomfortable with it because it's particularly supernatural, and maybe even more so because it plays again on that fear that our faith makes us sound unbalanced. It's the suggestion that sometimes, God chooses to speak through an actual, audible speaking voice, like that of another human there in the room with us. The question is – are we scared of this phenomenon because we think people who report it are probably making it up...or because it might be real?

In the Old Testament, God speaks to chosen leaders and prophets all the time in an audible voice. That's the implication throughout (although some might argue that voice of God is interpreted by the prophets, rather than directly heard), and sometimes it's made entirely explicit, such as on Mount Sinai in Exodus, where God tells Moses directly what how to direct the people. In the New Testament, God speaks to man directly and audibly, but only through the person of Jesus. Some would argue that this indicates that the days of a voice from heaven are over, thanks to the arrival of Jesus and then the Holy Spirit. But to confuse things somewhat, in Acts 9 (after his Ascension) we find Jesus speaking to Saul and then Ananias in an audible voice – so there is a little precedent for such communication.

Given that God is all-powerful, no one doubts that God could choose to speak audibly in 2018. The question is over whether he actually does, and opinion on the answer is somewhat divided. So allow me to throw in a personal story, which inescapably defines my position. I believe that I have heard the audible voice of God, speaking to me.

I have been a Christian for 25 years, and it has happened twice. The first time was when I was 19 – running errands for the children's camp I was working at. I know precisely where I was, and some 20 years later I continue to absolutely believe that God told me something about my future. It was the calm, assertive voice of a man (although I'm sure he doesn't have to use a male voice), and it absolutely transfixed me. The actual suggestion was a fairly extraordinary prophecy, and some two decades later it's probably halfway to coming true. Of course I wish there was a neater resolution, but I still believe not only that I heard God that day, but that what he apparently said will come to fruition.

The second example is perhaps a little more striking, and yes, neat. I was 25, in Dallas at a conference, and two days from taking a flight to another part of the USA for a meeting which could have had a fairly exciting impact on my writing career. I woke up suddenly – it's important to really stress that I was absolutely awake at this point – and heard that same voice telling me to forget the meeting and go home. It was so clear and sure that my body rushed with adrenaline – and even though I was desperate not to cut short my trip and miss the meeting, I just knew I had to.

I was immediately entirely awake, and so roused my travelling companion and shared my story with him. He was a little unsettled but agreed that it was probably God's voice that I had heard, so I called the airline (and called the meeting off, which never got rearranged), and went home. And when I did, all I can say is that my early return was vitally needed by my family, in a way that I couldn't possibly have anticipated. It was a moment where I believe indisputably that God chose to intervene in my life, and l believe that he did it through speaking out loud.

You may read this with disbelief, or even a nodding sense that yes, I am indeed mad, but it's my story and I'm sticking to it. So if God can theoretically choose to speak audibly today, and if stories like mine (there are many others) suggest that perhaps he actually does, is it something about which to be nervous, or to keep an open mind? As much as I don't want to hand ammunition to those who might want to ridicule my faith, I can't deny that I believe God does choose, rarely and in very important moments, to communicate in this way (and for the most part of course, not to).

A God who manifests himself in such a tangible way is perhaps a little scary because such supernatural phenomena makes his power suddenly more real. But let's not be tricked into limiting him; that's precisely the agenda of someone who would tell you that Christians are the people who hear voices. Maybe sometimes we do.

Martin Saunders is a Contributing Editor for Christian Today and the Deputy CEO ofYouthscape. Follow him on Twitter @martinsaunders.