I once knew a man who was a chaplain for a major organisation. As you would expect for any Christian minister, his duties included taking services for all who wished to attend and ministering to people's general spiritual needs.

One time, after he had conducted a service, the chaplain's boss, who was also in charge of the whole organisation, drew him aside for a quiet word. 'There was a bit of a problem with that,' the boss said. 'I was okay with some of what you did. But there was really rather too much mention of Jesus.'

And that, in a nutshell, is the fatal spiritual mistake that it is so easy for people to make. They love a bit of religion, or perhaps are attracted to an aspect of Christian ethical teaching such as being kind to others – but when it comes to Jesus, they turn away.

This, too, was exactly the error that many of the religious leaders to whom Jesus originally spoke were making. In Mark 12v1-12, Jesus tells a story in which he challenges their lack of spiritual fruit and denounces them for consistently rejecting God's messengers.

At the end of his parable, he throws in another picture – this time to do with building works. Again using an illustration from the Old Testament (Psalm 118v22), Jesus imagines a group of builders who reject one particular block of stone, believing it to have no place in their construction. Tragically, Jesus says, they have actually rejected the very stone that was essential – the one that was exactly the right shape to be the cornerstone or capstone (the word can be translated either way), and thus vital to complete the building.

The message is clear: these religious leaders loved 'religion' – but they were missing the main point of what true faith is all about. It's not, primarily, an ethical code or an abstract set of doctrines: it's all about the person and work of Jesus Christ. And we all need to be clear about this.

1. Is Jesus Christ a building block or stumbling block for you?

To use current figures of speech in line with Jesus' illustration, Jesus can either be the essential building block on which we construct our lives – or he will be a spiritual stumbling block over which we fall. Jeremy McQuoid comments: 'It reminds us just how personally God takes our response to the gospel. The gospel is not a set of propositions to believe, but a glorious person to be embraced... All of God's plans for the future of our world resolve around Christ, the cornerstone.'

2. Will Jesus Christ make you or break you?

In Matthew and Luke's account of this same event, there is an extra comment (Matthew 21v44): 'The one who falls on this stone will be broken to pieces; and it will crush anyone on whom it falls.' Leon Morris writes: 'To fall on the stone or have the stone fall on you in either case means destruction. People may reject and oppose Jesus but it is they, not he, who will suffer.' And Richard Lenski says: 'Judgement can be pictured with no greater severity.'

3. Are you about to make the same mistake as Jesus' original hearers?

How did Jesus' first listeners react to these challenging pictures? 'When they realized that he had told this parable against them, they wanted to arrest him,' Mark tells us. Their reaction is not to reach out, but to reject – a course of action that would ultimately lead to Jesus' execution. So if you are reading this as someone who is not yet a Christian, the challenge is clear: will you, like them, react by taking offence? Or will you – please – take time and trouble to consider seriously who Jesus is and to discover more about what it means to trust him?

And if you are a religious leader, as I am, there is also a challenge: are we so busy about our spiritual activities that we are forgetting what – or rather Who – it is all about?

Devotional writer Scotty Smith sums it up so well: 'You are the life-giving living Stone... The more precious you become to us, the more we watch our shame, fears, and confusion melt away. The more we see you for who you are, the more we see all other currencies as fool's gold. The more we come to you, Jesus, the more we realize that it's you who is always coming to us first.'

Perhaps, for you, he's doing that even right now.

David Baker is a former daily newspaper journalist now working as an Anglican minister in Sussex, England. The Rough Guide to Discipleship is a fortnightly series.