One of the hottest trends in New Testament Studies is to see the gospel proclamation in the New Testament as being explicitly anti-imperial. Jesus was called 'lord' and 'savior' in the New Testament. The proclamation about him is called, 'the gospel.' Interestingly, Caesar was also called 'savior' and 'lord.' And proclamations about him were sometimes called 'gospel.' Does this (and other evidence) suggest, though, that the gospel was explicitly anti-imperial?
Not to be a downer, but I think some of the enthusiasm about the anti-imperial nature of the gospel should be tempered. That's not to say that there's no critique of the Roman empire present, but, in my opinion, two things mitigate against this now very popular understanding of the background against which the gospel is supposedly best understood.
First is that the book of Acts repeatedly stresses that the gospel isn't anti-imperial. Notice in many cases, blame for being driven out of the city is placed on some Jews who stirred up trouble. There's also the notable case in Corinth where the magistrate declares that Paul's teaching was not seditious (Acts 18:1-14); I could bring up other instances from Acts as well. Some suggest that Philippians should be understood an anti-imperialist letter, but I don't see how that does justice to the text. Even at first glance, how could Paul be so confident of his acquittal before Caesar if his gospel was an attack on him (Phil. 1:19-26)?
What, too, do we make of the trial and crucifixion narratives? Specifically I have in mind Matthew 27:11-26. It seems obvious that even while Jesus admits to Pilate that he is king of the Jews, Pilate doesn't see this act as seditious!
I don't want to swing too far the other way and say that there is no critique of the Roman empire and Caesar in the New Testament or in a correct understanding of the gospel. I just do not see it as a primary category for aiding us in understanding the gospel or the early Christian movement. I believe that the Old Testament still forms the primary source from which the early church took its terms for proclaiming the truth about Jesus.