I recall one former General Director of the Evangelical Alliance stating that if you call out 'evangelical' these days you never quite knows who is going to answer. Evangelicalism, he said, consists of a big extended family in which legitimate membership has drifted across cultures, church styles and doctrinal emphases Evangelicals are open, progressive, mainstream, left and right, post or radical, conservative or fundamental. They can be charismatic, Pentecostal or Reformed.

The word is certainly very elastic, and until recently wasn't one that found a sympathetic hearing either. Indeed I can remember a time when the leaders within the Evangelical Alliance felt the need to rescue and redeem the word because it seemed to have so many negative associations.

How heartening then to hear the Prime Minister of all people challenging Christians to become more evangelical in their faith. I wonder if he knows what he means by this though, and just as importantly I'm asking myself why he is pushing this particular button at this moment in time.

I don't doubt his integrity but he is an astute politician, and he would not be doing his job if he was not scanning the cultural scene to see which parts of the electorate he needs to win - or win back given his current welfare reforms and his obstinate refusal to allow more time and discussion on the issue of same-sex marriage.

Sadly it seems to me that while contending that Christians should be "confident in standing up to defend" the Christian values of "responsibility, hard work, charity, compassion, humility and love", and should feel able to speak up about their faith in an "ever more secular age", he has allowed his understanding of the faith to be shaped by a his own (secular) agenda.

Having said that though we should only welcome his endorsement of the church and his recognition that Christians can and do make a huge difference to peoples' lives. Our history bears witness to that undeniable truth just as a wealth of food banks, money advice centres, parent and toddler groups for example are evidence of the impact tens of thousands of ordinary Christians are having in our communities today. It's the same with the Street Pastors initiative. I am currently promoting one in my own area and was delighted to discover that our new Town Clerk had experience of Street Pastors and was immediately enthusiastic when I approached the Town Hall a few weeks ago.

So what is an evangelical? The following four points, adapted from key studies of the movement by David Bebbington and Alister McGrath, represent a workable summary of Evangelical characteristics.

• Evangelicals are known for their recognition that Scripture should guide and shape everything they believe and do.
• They are identifiable by their confession that Jesus and Jesus alone can put us right with God through His death on the cross.
• They are sold out on conversion, recognising the need for people to make a personal commitment to Christ
• All these other fundamental truths provide the motivation for the social action Mr Cameron so readily applauds

Given the fact that so few people now identify themselves as Christians I wonder how he can argue that we should be more confident about our status as a Christian country. As I see it any full-blooded evangelical would be concerned about the spiritual state of our country and long to see people coming to faith in the crucified and risen Lord.

And given his other observation that he is "not that regular" in attending the Church of England and "a bit vague on some of the more difficult parts of the faith", I am wondering if a national revival could begin with the Prime Minister himself. Now that would be some Easter message to shout about.