The Loyalists maintain their belief in the Source, including His initial mission to perfect and protect his greatest creation: human souls.
The Loyalists are divided into hierarchical groupings. Archangels are the generals who organize and lead the other “worker” angels–the Hoard. There are also two more groups, individuals who have been hand-picked from the Hoard to create the Advocates and the Watch.
In Earth terms, if the Watch were deemed to be the “special forces” or prize-warriors of the Hoard, then the Advocates would be compared to the highest level of judicial court.