Reviewing the statement from https://www.christiansagainstchristiannationalism.org/statement

These "judeo-christians" renounce Jesus Christ as their Monarch just as the Jews of two thousand years ago: When Pilate said, "Behold, your King!" the Jews said "We have no King but Caesar!"  This "statement" says the same thing: "Jesus is not our Monarch -- we swear allegiance to a constitutional democracy devoid of Jesus Christ!"  They are traitors to Jesus Christ.