Empirical Support for the Postmillenial Mustard Seed

Committed Christians to Non-Christian (n/1)

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"Another parable put he forth unto them, saying, The kingdom of heaven is like to a grain of mustard seed, which a man took, and sowed in his field:  Which indeed is the least of all seeds: but when it is grown, it is the greatest among herbs, and becometh a tree, so that the birds of the air come and lodge in the branches thereof." (Matthew 13:31-32) 

 I emphasize that this is empirical support, by no means it is it a demonstration of postmillennialism.

Still, there is some reason for optimism; I take postmillennialism to be the most optimistic of the Christian positions on eschatology.  Aside from spiritual virtues specific to Christianity not held by most others, here are some other positive effects that Christianity has arguably contributed to civilization (though I will not argue for this historical claim, and I'll ignore contributing causes):

The abolition of widespread slavery
The creation of the modern university and mass education
Hospitals
The elevation of subjugated women to equal status with men (including among other things in education)
The seeds for the Enlightenment, and with it, liberal democracies
The diminishing of mass poverty and starvation

Condemnation of racism and civil rights for the vulnerable

Empirical support for pessimism regarding postmillennialism: The World Wars and mass atrocities of the 20th Century.