That's true, but we do not yet reign on earth:
Rev 5:10 And hast made us unto our God kings and priests: and we shall reign on the earth.
Read the context of Rev 5:10 beginning with verse 1. The "shall" began when Jesus assended into heaven and went before the throne of God. Did that event transpire upon His return to heaven or is it still future? Yes, we rule today; as Paul says "We are more than conquorers (Rom 8:37)