Ehrman tends to make assertions he cannot know to be true. For example, here Ehrman claims that Paul prior to his conversion had been persecuting Christians for their belief in the resurrection. How does he know that?
It's not clear whether you are skeptical about whether Paul persecuted Christians or whether those Christians believed in the resurrection....Obviously Christians have always believed in the resurrection, so I don't doubt that the Christians of Paul's day believed in the resurrection. What I do doubt is that Paul was persecuting them if that persecution involved armed violence. The Romans were not known to stand around while the people they had conquered ran around with weapons.