This is the script of this morning’s Thought for the Day on BBC Radio 4’s Today programme.

“And did those feet in ancient time walk upon England’s mountains green?” Well, no, actually – probably not. But, William Blake’s questions are not to do with historical event or fantasy, but with the need for a vision of England itself that transcends present miseries. Reality can only take you so far, after all.

A new Blake exhibition opened last week at Tate Britain in London and it has provoked huge interest. As someone who has never quite understood him, I look forward to seeing it and having my imagination opened more widely by seeing the world through Blake’s eyes. For what is clear about him is that his poetry, art and writing sees him wrestling with what it means to be truly human in a troubling world.

In his work we see Blake struggling personally with what was going on around him. Political oppression, public fear, uncertainty about the future in a changing world – he faced reality with imagination, vision and thankless political commitment.

However, vision wasn’t enough: he took seriously his own responsibility for addressing the world he questioned. The ‘satanic mills’ were a source of England’s prosperity, but they relied on draining human beings of life and soul; children might fit into chimneys, but that didn’t mean they should be sent up them – especially by people who then went to church to praise God.

It seems to me that Blake understood what is easily forgotten by Christians like me: that those who claim God’s name should at least begin to reflect the character and priorities of God. In other words, if I truly believe – and claim to be motivated by – the God of the Bible, in whose image every human being is made, then I cannot support or collaborate in language, policies or actions that diminish people.

Now, Blake recognised that this isn’t a black and white matter. None of us simply switches a moral dial and suddenly becomes perfect or consistent. We are not only fallibly human, but we also live in a particular social, historical and cultural context. The most we can do is try to see clearly – which means having the humility to allow the lens behind my eyes to be re-ground – and live differently, despite everything.

Blake worked out his salvation in vivid and glorious – sometimes terrifying – image. Words opened up the possibility of the divine – a spirituality of hope and justice in a world of grinding misery and material poverty. In looking through his eyes I hope we might find our own opened to look differently and see differently – what I would call the beginning of conversion.

Agreeing with Blake’s vision is not the aim. Engaging with its struggle is. Because in engaging with his mystical vision of God and humanity we might find ourselves inevitably driven to what these look like in real flesh and blood. To seeing “Jerusalem builded here”.