Start by doing some research on the two people in question. Make a point form list of their ideas on nationalism.
If you were just evaluating them from your own perspective, then you would simply ask yourself if you agree or disagree with those ideas. If you agreed, you would jot down the reasons why you agreed. If you disagreed, you would write down your reasons for thinking they were wrong. If you agreed with some ideas but not others, you might end up with two separate lists. These lists would be the beginning of your evaluation.
In this case, though, you have to go one step further. You need to read up on Christ's teachings, and decide whether someone who followed those teachings would agree with those or ideas or not, and then explain why or why not. So, same process as outlined above, only pretend, when creating your lists, that you are a devout Christian who sees the world through the lens of Bible's teachings. That's the approach part.