It has nothing to do with todays Christians as they have passed from condemnation to life (Jn 5:24).
It's a judgment of the nations (v.32), as to how they treated the Jews during the GT.
Matthew 25:34
34 “Then the King will say to those on his right, ‘Come, you who are blessed by my Father; take your inheritance, the kingdom prepared for you since the creation of the world.
Some of the nations will inherit a kingdom, but they aren’t Christian? Also, you mentioned the GT. When was or is the GT?