People were saying, "He has gone out of his mind..." (Mark 3:21)

What's the biggest decision you have faced so far? I agonised over how to cast my vote in our UK General Election.

I have always participated in elections since being old enough to do so. But this time, unusually, I struggled to know whom to support.

It's not the biggest decision I've faced, naturally. Getting married was a key one, as was testing out a call to ordination. But, of course, there is something even more life-changing we all have to decide.

As we continue our walk through Mark's gospel we reach a section where big decisions with fateful consequences are being made.

Jesus is so beset by crowds that he can scarcely eat, and so his family decide to try and take charge of him, "for people were saying, 'He has gone out of his mind'" (Mark 3:21). They think he's mad.

Some of the religious leaders have also made a decision. Jesus, they opine, is nothing less than demon-possessed. "He has Beelzebul," they decide, and so it is "by the ruler of the demons he casts out other demons" (22).

Meanwhile Jesus himself is pronouncing with authority on who – and who will not – be forgiven (28-29). Moreover, he declares that "whoever does the will of God is my brother and sister and mother" (35).

It was this section of Mark's gospel, of course, which led the Christian apologist CS Lewis to suggest that we have to decide whether Jesus is mad, or bad, or God.

He famously wrote: "I am trying here to prevent anyone saying the really foolish thing that people often say about him: 'I'm ready to accept Jesus as a great moral teacher, but I don't accept His claim to be God.' That is the one thing we must not say. A man who was merely a man and said the sort of things Jesus said would not be a great moral teacher. He would either be a lunatic – on a level with a man who says he is a poached egg – or else he would be the devil of hell. You must make your choice."

More recently Bishop Tom Wright wrote: "There is no middle way ... Jesus isn't just a 'mildly interesting historical figure'. He is either the one who brought God's kingdom, or a dangerous madman."

For some of us this may be a new idea. There is much more to be said, of course. But it is not a bad place from which to start. Get hold of a Gospel (perhaps Mark itself), read it through, and ask yourself what decision you will make about Jesus, remembering that not to decide is a decision itself – and that, if Jesus is right, there are eternal consequences.

For others of us it may be a very familiar idea. We've been there, done that, ticked the doctrinal boxes, got the "mad, bad or God" t-shirt, and may – possibly – think that in some way, shape or form we have moved beyond all that sort of thing now.

But may I suggest we would be unwise to do so? The Jesus who walks out of the gospel and confronts us here will not let us settle into complacency about him. As one commentary on this section puts it: "Have you settled for a pale caricature of Christ you feel comfortable with, and lost sight of the real Jesus who calls you to die to yourself, set aside every competing allegiance, take up your cross and follow Him?"

On the basis of your life, then, what sort of decision do people think you have made about Jesus?

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