The Congregation of Finality are the last souls of an entire race, which gives the soul extra power. They are housed in the Congregational, which means doom for any who see it. All the souls are linked together and they listen to all the prayers of the Uni-Lord's followers. This gives the Uni-Lord power and sustains him. There is no escape from the Congregation.
When the Silver Surfer came to this universe in an attempt to stop the Uni-Lord and his Blackbodies he was taken into the Congregation. But since he was not the last of his race he was able to resist the control. Secretly, his soul was also combined with that of Oclin Uwir Prin and this caused the Uni-Lord to weaken.
He soon found that Norrin Radd's soul was corrupting the Congregation and replaced it with that of Pradda Fol. But Oclin was still undetected and combined with his soul as well, leaving the corruption intact.
The Congregation was overloaded with prayers when the Uni-Lord attempted to assimilate the worlds of all the Skyriders. The Uni-Lord attempted to defeat the Surfer with the Congregation fighting for him. The Surfer discovered an Iridian and knew this must be who took his place. Knowing what would happen, he destroyed the Iridian and caused a chain reaction that did the same to all other members.
The defeat of the Uni-Lord at the Silver Surfer's hands meant the end of the Congregation and all the souls died, excluding Skooka, who was born anew.