5:10 "And Thou hast made them to be a kingdom and priests to our God; and they will reign upon the earth."

And THOU hast made them to be a KINGDOM and PRIESTS to our GOD;

Three times in Revelation (1:6: 5:10; 20:6) we, the believers, are to be made kings and priests. The sense of this phrase indicates this is in the future -- perhaps, the millennial reign. Scripture is clear, though, we believers are being built up into a spiritual house (1 Peter 2:5). Part of our priestly function is described in Hebrews 13:12-16.

and they will reign upon (over) the earth."

This can only happen in a limited sense before the devil is bound. After the "ruler of this earth" (John 12:27-32) is cast out, then this really can take place.

How this "reigning" happens is a mystery. Whether the redeemed "commute" from the heavenly "new Jerusalem" to the earth is not clear. What is clear, though, the martyrs from the tribulation will come to life and WILL REIGN with Christ (Revelation 20:4-6).