Wrong.
Wilberforce did not get slavery criminalised, he got the slave trade criminalised (in 1807). There were still slaves after that until slavery itself was criminalised in 1833.
To claim that his work had anything to do with being a Christian is absurd. So called Christian values held sway in Europe for 1600 years prior to any Christians actually getting off their arses to stop slavery.
So no Christians released slaves in the Roman period.
Didn't Augustine write on how appaling he found slavery.
That a society that called itself Christian let bad things happen is certainly regrettable although it is debatable that the rule of Kings in many places amounted to utter theocracy anywhere.
The picture Jeremy P paints is that it took secularism to persuade naturally rabid slave wanting christianity to get rid of slavery (see my earlier post on the likelihood of that).
Well Jezzer we now have an increasing secular society and slavery is making a come back. Do you think that's because secularists didn't get off their arses to stop it's reintroduction?