There may have been a pax Romana, but that doesn't mean that everything was peaceful and lovely in the Roman Empire. The way they maintained the peace was with an iron fist. What that means is that at the very first sign of trouble they would round up the leaders and execute them.
The Roman Empire executed Jesus just like they executed over hundred other rebel leaders. What makes Jesus extraordinary is not that he died on the cross. That was a typical execution method for political prisoners. What makes Jesus extraordinary is that he defeated death. He rose from the dead and showed himself not just to the disciples. It happened over 2000 years ago, and we're still talking about it.
Here is a hipster version of "Christ the Lord Is Risen Today." Happy Easter!