Can you also provide evidence that anyone was "immediately killed" by the Romans for suggesting that slavery was wrong?
My evidence is common sense. You don't admit to being a Jew at a 1940 Nazi meeting and complain about force Jewish labor camps if you value your life.
You seem to think that the Romans were just good ol boys who were interested in the good of all. People were getting crucified back then for things like theft. And the Romans allowed Jesus to be crucified even though they thought he was innocent. You don't challenge the ways of a conquering army (in an open way) if you value your life.
And Jesus' main priority was eternal matters, not the things of Caesar. Jesus' way wins in the end as Christianity became the main religion of the Roman Empire. And the Greek and Roman gods ended up on the ash heap of history.