They come when humanity is in it's final hour,

When the world is corrupted and most souls are sour.

They bring an end to the sinning of man,

And initiate the next phase of God's plan.

When the water is contaminated with horrible disease,

It will make crops fail and spoil the trees.

When food is scarce, people will war and kill,

Gaining food or gaining death, each man will have his fill.

The horsemen embody the worst parts of our lives,

And will know it's end as our population number dives.

The whinny of their horses makes a soul shattering roar.

Who are these horsemen? Name all four?