No king but Christ.
Sola Fide
Sola Scripture
Sola Gratia
Solus Christus
Soli Deo Gloria
"For there is one God, and one mediator between God and men, the man Christ Jesus" -- 1 Timothy 2:5
I don't think restoring unity to Christ's Church will be accomplished merely by commanding or inviting all Christians to become Reformed Protestants. I think it will take a patient but determined commitment to dialogue (in a manner similar to what I just laid out above) between Christians of the various traditions.
-A8