Do you know of an instance where a founding Father who was Christian did not give Godly treatment to the slaves in his care?
Ollie - that's right!
Jesus never addressed the question of 'slavery' as we recognize the term. Why? Because during His time on earth it was not a matter which was at the 'top of the social order' of things to address. In other words - slavery just 'was' and it was accepted. Slavery meant many things then - from indentured survitude (paying off a debt) to captives of war being enslaved, to entire races of people being enslaved simply because of that - their race.
But if you will remember, Jesus healed a slave (servant) of a centurion(?) from afar simply because the centurion had faith. (And - I bet - the servant had faith after that! Praise Him!). Also, Paul sent a slave (servant) back to his master with the message to the master (slave owner) to accept him and love him and not punish him.
So – considering a founding father not to be Christian due to keeping of slaves is not consistent with biblical teaching.
Does slavery suck? Yes. Is slavery eternal? Only if you are a slave of Satan.