Jerusalem

But the religion of Jesus, forgiveness of sin, can never be the cause of a war, nor of a single martyrdom.
- "Jerusalem", William Blake

"Jerusalem" is a long prophetic poem by William Blake, which is sort of like reading Jeremiah or Ezekiel in the Bible. All of these are warnings to those who will listen, of all the things of this world that lead us astray, and how it all has consequences. At the beginning of the poem, Blake addresses the Jews, the Deists, and then the Christians. Blake writes of how we stray and in self-centered pride we set ourselves up for a future where we use our power to oppress others. Isn't that what we see so much of around the world? Oppression?

Awake! Awake O sleeper of the land of shadows, wake!
Expand!
I am in you and you in me, mutual in love divine.

There are some deeply beautiful poetic passages throughout, but also some dead-on truth that speaks to us today, even as Blake wrote it between 1804-1820.

Blake states quite bluntly, it's either follow Jesus, or follow the world (Satan), because we all will and must follow something. However, there are those who say there is a God out there who is all powerful and yet doesn't take part in our lives (the Deists). They think of God as a clock maker, who created the world and then stepped back to let it run on its own. In this, then, they have made their own God of this world, which Blake refers to as the natural philosophy and morality.

When Satan first the black bow bent
And the moral law from the Gospel rent,
He forg'd the law into a sword
And spill'd the blood of mercy's Lord.

It is the make-your-own and whatever-makes-you-happy view (whether or not that follows Jesus) that is the enemy. Following Jesus is not a pick-your-own religion whereby you can choose what to listen to and what to ignore, or what to be virtuous in while accusing others of their faults, while being a hypocrite yourself. Blake compares those people to the Pharisees, and I think even our modern day has far too many Pharisees, for it is such an easy trap to fall into. It is the way of the world, and Blake reminds us that any religion that preaches vengeance for sin is a religion of the enemy. Do we forget that God says "vengeance is mine"?

Our job is to forgive. To follow Jesus. 
Blake writes that the glory of Christianity is to conquer by forgiveness. How different would our world be if more of us lived like this, wholeheartedly?

For a tear is an intellectual thing,
And a sigh is the sword of an angel king,
And the bitter groan of a martyr's woe
Is an arrow from the Almightie's bow.