The revelation that German Chancellor Angela Merkel had her mobile phone tapped by American intelligence officials has caused a storm of protest from European leaders.

But it's only the latest news in an unfolding story which has brought to light huge programmes of covert surveillance being undertaken by the US National Security Agency and Britain's GCHQ.

Information leaked by whistleblower Edward Snowden to The Guardian and other newspapers has shown that there has been unprecedented mass surveillance by both the United States and UK.

In another development, Spain asked the American ambassador to explain reports that his country's security services had monitored 60 million Spanish telephone calls in one month alone.

Meanwhile, in a separate but related story, two former editors of the now defunct News of the World are on trial over charges relating to phone-hacking.

All these issues raise questions in our minds about how secure our own privacy is. Who, perhaps, has been reading our e-mails? Who has been listening to our phone calls? And can we be sure of keeping anything really confidential in this kind of world?

We like our privacy. And while we recognise that a certain amount of covert surveillance is necessary for our security, the thought that our own personal space might be invaded without our knowledge is quite an unsettling one.

But too often our privacy is a convenient cover for things we would prefer to keep secrety. Unless the Watergate tapes had come to light, President Richard Nixon's misdemeanours would never have been exposed. Equally, with our own private lives, unless there is fear of exposure, things can easily veer out of control: as someone said to me not so long ago about a struggle they were facing, "The only thing that stops me is the fear of being caught."

Of course, what we aim to conceal can come to light unexpectedly. We can be overheard when we are unaware of it. Or, as the Old Testament puts it rather whimsically: "Do not revile the king even in your thoughts, or curse the rich in your bedroom, because a bird in the sky may carry your words, and a bird on the wing may report what you say," (Ecclesiastes 10v20).

But much more than that, it's a sobering fact to remember that God is aware of all that we do, say and think – and that all these things will be one day brought to light. As Jesus puts it, while warning against hypocrisy: "There is nothing concealed that will not be disclosed, or hidden that will not be made known. What you have said in the dark will be heard in the daylight, and what you have whispered in the ear in the inner rooms will be proclaimed from the roofs," (Luke 12v1-3). And elsewhere he says starkly: "I tell you that everyone will have to give account on the day of judgment for every empty word they have spoken." (Matthew 12v36)

Equally, however, this same truth can be a tremendous comfort. In Psalm 139, David addressed to God these famous words often used at funerals: "You are familiar with all my ways. Before a word is on my tongue you, Lord, know it completely." His next thought is of the great reassurance this brings: "Where can I go from your Spirit? Where can I flee from your presence?"

God is listening to your every word and thought. And mine. Today, do you need to hear that truth as a challenge – maybe as a wake-up call? Or do you need to hear it as a comfort, and sleep peacefully tonight?