Pliny, Trajan, and the Christians
By the time that Trajan was the Roman Emperor, around 100 AD, Christianity was definitely illegal. We have some letters written by Pliny, the governor of Bithynia (in Turkey) to the Emperor Trajan, asking for advice about some Christians Pliny had found in Bithynia. Pliny understood that if the Christians confessed they should be killed, but he wasn't sure what to do if they insisted they weren't Christians. And what if they had once been Christians but they weren't anymore? Trajan answered (we have his letter too) that if they denied it, or were no longer Christians, they should be let go. They should only be killed if they said they were Christians now. Mostly, he said, they should be killed because this showed disrespect for the governor. And, Trajan said, Pliny should not go out looking for Christians either. He should only investigate if they drew attention to themselves or if somebody else accused them. And he should not take any anonymous accusations.
Bibliography and further reading about Pliny and the Christians: