Full disclosure: U2 has been my favourite band since I was a schoolboy (apart from a brief liaison with REM in the '90s). I bought all their t-shirts and even hitched to France for a gig that felt more like a worship service than a rock concert.

As well as respecting their music over the decades, I love the fact that Bono has used his platform to champion global justice. So I am by no means a U2-hater, but even I have to acknowledge the massive backlash over Bono, Larry, Adam and the Edge's recent project with the technological behemoth Apple.

The seemingly benevolent act of giving away Songs of Innocence free on iTunes proved to be a PR disaster for both U2 and Apple, with unprecedented amounts of social media anger directed at both parties. Fellow musicians also stuck the knife in, with Pink Floyd's drummer Nick Mason only this week saying the giveaway 'devalued music'.

However, a session talking to fans on Facebook in which Bono apologised, a charming appearance on a prime time chat show poking fun at the whole endeavour, and a swift addition from Apple in the form of a one-click removal tool, seem to have helped the furore start to die down.

As Christians who are also seeking to give away our faith each day to millions of people around the globe, I wondered if there were lessons we could learn from this fascinating cultural faux-pas and its aftermath.

1. Don't be pushy

I am pretty sure that if U2 had simply made their new album free to download to anyone that wanted it there would have been universal applause. The problem was that the album was pushed out to everyone's iCloud account which meant everyone with an IOS device received it automatically. 

Sometimes we use 'push' language in evangelism. We ask Christians to take the initiative in conversations, give away leaflets, pamphlets, and books, fight to put Christ into Christmas, and persuade people to come to free events with free meals, free childcare, free entertainment. These strategies often produce a limited response, firstly because many Christians seem to be nervous about coming across as 'pushy' and secondly because pushiness evokes scepticism, disbelief, and mistrust in our unchurched friends. The widespread negative response to U2's free gift underlines this awkwardness. We need to take heed of the fine line in our culture between promotion and propaganda, and encourage Christians to be intentional about sharing their faith, without being pushy.

In 1 Peter 2:11 we are encouraged to "Live such good lives among the pagans that, though they accuse you of doing wrong, they may see your good deeds and glorify God on the day he visits us." Two aspects are in play here - proximity and provocation. There is a proximity expected, a relational connectivity between the Christians and others in the community. But there is also to be a provocative lifestyle from the Christians that elicits questions and promotes interest from those they are in relationship with.

2. Expect your motives to be critiqued

There was a lot of conversation about what U2's motives were. Was it to boast that their album is the most downloaded album of all time (500 million and counting)? Was it to promote sales of their back catalogue? Was it to resurrect a waning band? Was it to underline the devaluation of the music industry? Or was it simply a massive marketing stunt?

"There's no such thing as a free lunch." That is what one student said to me when I handed him a flyer for a (free) evangelistic lunchtime event. He was right of course – I was trying to buy his attention for half an hour through the provision of some food. Many of our evangelistic strategies operate on this principle. Free holiday clubs that have an ulterior motive of adding families to our regular services? Generous services to the community that are just trying to buy their respect or their agreement for a planning application?

Perhaps we should be a bit more transparent in our evangelism and a bit more selfless about our social justice work. Offering freebies to lure people into attending events may be counterproductive. Serving the social needs of our society is the right thing to do, because it honours God, and helps us to demonstrate the kingship of Jesus over all of life. This won't stop our motives from being questioned, but perhaps that is no bad thing.

3. Be transparent about finance

Part of the angry discussion was about the amount of money that U2 were paid to offer the album as a gift. The New York Times said it could have been as much as $100 million. Some of the anger could just be jealousy at U2's ability to command such a huge figure, or latent envy of Bono's shrewd business sense (remember this is the man who personally made hundreds of millions through his early investment in Facebook).

Christians need to be utterly transparent about money, especially when it comes to evangelism. With mega-church pastors, prosperity teaching and fallen televangelists there is enough negative publicity around evangelism to justify a lot of the cynicism surrounding the sharing of our faith. Ordinary people sharing the gospel with one another is much more effective than the international evangelist who travels first class.

4. Recognise social media is someone's reality

There was such a powerful and vehement online response to the U2 album giveaway. Angry, polemical and sarcastic tweets were quickly re-tweeted. So were many of the tweets from the Apple live event – saccharine-sweet worshipful compliments on the beautiful and revolutionary communication devices that Apple had created. There were very few average, middle ground, dispassionate responses.

But these tweets, both good and bad, determined the perceptions of these devices, and in marketing perception is reality. The iPhone 6 and 6 plus have been the best-selling phone releases of all time – most people pre-ordered them before they had the chance to try them out. So the social media perception was the only reality needed for people to invest in some of the most expensive mass produced phones of all time.

For some people, their only exposure to the gospel is seeing their Christian friends on social media. We need to be mindful of this. Some of our online battles on secondary issues, some of our derogatory words about other believers are perception-forming for a watching world. But on the other hand, some of the online acts of kindness, championing of the poor, generosity and compassion can also shape how our friends will perceive the gospel.

We the church are seeking to give away the most amazing gift in human history – the good news of the grace of God. In our enthusiasm we must be careful not to be pushy, to make sure our motives are as pure as possible, that we are utterly transparent in our handling of money and that we make the best use of social media to represent the reality of the grace of God. After all the fuss, it turns out that Songs of Innocence is (in my humble opinion) actually pretty good. Why not give it a listen? After all, chances are you already own it.

Dr Krish Kandiah is founding director of the charity Home for Good and President of London School of Theology.