I remember thinking how ironic it was. The mandolin of R.E.M.'s signature song of the 90s was playing on the radio and that was the moment my friend chose to tell me he had lost his faith. Although 'Losing my religion' apparently was not written about losing faith but refers instead to losing patience, or losing your rag. But I admit I was shocked and close to losing it myself. This person had been involved in organising cross-cultural mission teams, been on the leadership team of our university Christian Union and was the last person I imagined to be stepping away from faith. I didn't handle things well that day and since then I have often replayed the conversation, wondering how we might actually be able to help those that find themselves in this situation.

1. Thank don't freak

Looking back, I freaked out too much. In retrospect it is obvious that going ballistic is not going to help. For someone to let you into their inner turmoil is a statement of great trust. Surely it is better to express gratitude to those who confess to losing their faith, as, sadly, I think there are a lot of people that have come to similar conclusions but have not had the courage to let anyone else know and are slowly disengaging from the life of the church. By letting you know, the other person may well be signaling they are looking for some help. Let's begin always by thanking the person for their honesty and by asking them to explain a little bit about what has got them to this point.

2. Connect don't shun

Believe it or not I have had people quote scripture at me as to why we need to let go of people that have let go of their faith. "Friendship with the world is enmity with God" is one of the proof texts I have had lobbed in my direction to justify this approach. I am convinced this is not just an inappropriate use of the Bible (friendship with the world's godless system of values is what is in mind in this context) but also bad pastoral practice.

Jesus seems to have had a lot of time for those who find themselves on the fringes of the community of faith. He brought healing to a man's son who had been plagued by evil spirits, for example. Jesus' disciples had not been able to perform an exorcism which led to Jesus apparently "losing his religion" with his disciples: "You unbelieving generation... how long shall I stay with you? How long shall I put up with you?" (Mark 9:19). Jesus' frustration with his disciples unbelief did not lead to him abandoning his disciples, rather he further commits to help and instruct them. Indeed even when the resurrected Jesus appears to his disciples it is clear "that some doubted". The prayer of the boy's father on hearing Jesus' rebuke of his disciples is: "I do believe; help me overcome my unbelief!" And Jesus does – by healing his son.

What this little incident highlights is at least twofold: firstly, our unbelief in Jesus is a personal affront to him. It is like a vote of no confidence in Christ's character when we declare that we no longer trust him. This can be seen by the way that Jesus speaks very strongly and directly to his disciples for failing to perform a miracle in his name. And yet, secondly, Jesus remains incredibly patient and gracious in his commitment to his followers. They may have lost confidence in him, yet this is not going to be a deal breaker in their relationship with him because Jesus will graciously keep giving his followers more reasons to trust him. In the same ways, once our friends let us into their confidence and declare their loss of faith we must stay connected with them and show them that our friendship is unconditional.

3. Listen don't preach

When someone opens up about their crisis of faith we need to be "quick to listen and slow to speak." Let's be wary of jumping to conclusions before we have heard the person out. Someone who thinks they might have lost their faith might mean that they are currently wrestling with something they can't resolve – whether it's personal suffering, a part of the Bible they can't make sense of or a sense of the absence of God in their lives. This is different from someone who has come to a definitive conclusion that they are walking away from faith.

Actively listening by asking good questions can be a way that we understand where our friend is at with God. But it can also be a means by which we can help someone to see their situation in a new light. When someone says they don't believe in God anymore, we could ask them what it is exactly they don't believe about God. It might be that they had a flawed view of God to begin with and we can help them understand that we don't believe that about God either. If someone says that they don't believe God can accept them because of something they have done, we could ask them who they believe is acceptable to God on their own merit. It could be a wonderful opportunity to reaffirm the grace of God to all of us.

4. Love don't wimp out

It shouldn't need saying, but you and I are not Jesus. As we saw in the incident in Mark's Gospel, Christ can directly challenge the unbelief of his followers or indeed of the whole nation. In the end Jesus is the judge of all the earth and he will call to account for how we have lived, believed and thought. It isn't our place to look down in judgment on someone from a position of superiority. All of us are sinners saved by grace. Yet there are sometimes when we have listened as hard as we can, prayed for insight and yet still feel we need to offer a challenge. I admit it's been rare that I have felt it necessary to challenge someone's unbelief with words that were more of an apologetic rebuke than a pastoral response. But nevertheless there are times when we need to call a friend out for being a bit self-indulgent, deliberately obtuse or using a faith crisis as an excuse for doing something they know is morally wrong. As the proverb tells us "the wounds of a friend are trustworthy" (Proverbs 27:6).

5. Invite don't argue

I often ask groups of Christian university students if any of their friends have ever walked away from faith. Almost every time every one in the room puts their hand up. According to the statistics from Christian Research and the Evangelical Alliance there are still a whole group of young people that are deciding to leave the church and some of them are leaving their faith in God too. On top of this I have met a number of individuals who later in life have found both personal and global tragedies a reason to reject their faith in God. Often I have discovered that listening to their stories, even years later, inviting them to further exploration of some of their questions has been fruitful. This approach seems to help both intellectually and pastorally, and can often lead to a journey back to God, especially as they are invited to be part of an authentic church community.

I still can't listen to 'Losing my Religion' without thinking of all of my friends who no longer count themselves Christians. The mandolin's maudlin melody reminds me of the Father in the prodigal son story, his grief at losing a son, and his patience in waiting for him to turn his life around. That's when I find a bit of hope remembering that prodigals do sometimes come home. Let's not give up on praying for our friends who have lost faith. Lost things can be found again.

Krish Kandiah is a contributing editor to Christian Today. He is president of London School of Theology and founder and director of Home for Good. You can follow him on Twitter: @krishk