This carol is very old, reportedly sung in some form at the Feast of Corpus Christi in the early 15th Century, and some scholars think that the version sung today is actually three different tunes that were somehow melded together.
the author of peace and lover of concord;
to know you is eternal life,
to serve you is perfect freedom.
Defend us your servants in every stress and danger,
that we may trust in your defence
and not fear the power of any adversaries;
through Jesus Christ our Redeemer.
your kingdom come
on earth as in heaven.
Ruler of the everlasting kingdom,
prince of peace, champion of the despised:
you are the king;
you make a cross your throne;
you wear a crown of thorns;
you call your subjects friends.
Help us to take up our cross,
to hunger and thirst for all that is good;
then will your kingdom come on earth as in heaven