[Botanist]

(Hello! I'm a 3rd year religious studies major at the college I attend, and reading through the lore for the Essharan Church, I couldn't help but think that it was fantastic, but it could use some minor expansion, more or less giving clergy more to do. This is my attempt at that, using things I've learned over the past few years studying theology. Also, the name "Pantheon of the Celestials" doesn't roll off the tongue, so I'm proposing a new official name, too.)

The Essharan Celestial Church

More Flavorful Ranks
(I personally think that the current ranks within the Church sound a little too boring. This might add a little more flavor.)
1. Patriarch/Matriarch & Starseer (Grand Priest)
The head of the Church is selected directly by the monarch and can only be replaced upon their death or if they are rendered mentally incapacitated in any way, shape, or form. The head of the Church has to right to issue excommunications, appoint bishops, and has the final say in canonization.

As the most exalted position in the Church, the head is granted two titles that can be used interchangeably; one depends on the gender of the current head (if they do not feel like either, the neutral term "Parriarch" is used) and the other draws upon the Church's unbroken continuity with St. Niles of Astya, one of the seven starseers that founded Celestialism. Offhandedly, they are often referred to as "The Starseer."
2. Stellus (High Priest)
The stellii of the Church are selected directly by the Patriarch and have the power to ordain rectors and propose the canonization of a saint. There is one for each star in the constellation of Leonaus; once appointed, they cannot be demoted, and serve for life unless excommunicated or if they disavow the Church, allowing them to lead a secular life.
3. Rector (Priest)
Rectors make up the backbone of the Church. They minister to those within their selected area, collect donations, and perform charitable works to alleviate any temporal suffering they may encounter. The official way to address a priest is Rector [Name].
4. Deacon (Initiate)
Deacons occupy the space between the laity and the clergy; though not ordained, they often aid the rest of the Church in their duties, especially in collecting donations and performing good deeds. Some choose to go no further than this rank, leading a double-life in the clergy and in the world at large. The official way to address a deacon is Brother/Sister [Name].

Canonization
Canonization is the official process, established by the Church, in which deceased individuals of great faith and consequence are admitted into sainthood; sainthood presumes that the dead man or woman has lived so virtuously and that their spirit has been cleansed so deeply by the stars between their last life and this current one that their soul is admitted into paradise, living in everlasting joy at the side of the Creator.

Canonization is not a simple process. First, the canonization of someone who's died - the length of time does not matter - must be proposed to the head of the Church by a bishop. If the head of the Church approves, the candidate's canonization is voted upon by the bishops and then put forward to the head of the Church, who has the final vote on the matter.

Here are some examples of saints in the Essharan Church:

St. Mihail

Saint Mihail Petrakis was among the most prominent magi of the Astyan Empire and the spells he cast during the mythical age before the Divine War would be considered miracles today. It is thanks to him that the people of Astya were transported to Esshar, saving them from total annihilation. The patron saint of Esshar, all magi, and the royal family.

St. Niles of Astya

The founder of the Church and the theological father of Celestialism, no saint is more highly regarded than Saint Niles. He is the patron saint of clergymen, scholars, refugees, and House Pellaux.

St. Ermis

Saint Ermis was a lay healer who held a fragment of the Creator's soul; he performed miracles and sacrificed himself to save the world from Azrael's genocidal machinations. He is the patron saint of doctors, the sick, and Astya.

(It goes without saying that the Church would have more than three saints; saints canonized before the game would more or less be open-ended and left up to the players.)

Excommunication

Excommunication is the greatest and, as of 1660, only punishment that the Church can mete out. It is reserved only for unrepentant heretics, the morally bastardized, and practitioners of witchcraft. To be excommunicated is no easy feat and requires one to be completely, irrevocably evil, or a well-known and unrepentant heretic.

Firstly, the mere proposal of excommunication is voted upon by the Bishops. It is then passed onto the head of the Church, who reviews it and can either accept or deny it, and it is then passed onto the monarch for their permission.

Those who are excommunicated are not protected under Essharan law; they become, more or less, outlaws, hunted by the state and rejected by society at large. Survival after excommunication is no easy task.

The Katharistes

In times of religious crisis, be it the rise of a powerful heretical sect or impiety, the stellii and the Starseer have the legal right to petition the monarch to form the Katharistes, a long dormant judicial and militant arm of the Church that has the right to arrest and try anyone accused of heresy and blasphemy. The last time the Katharistes were formed was the 1400s; they operated primarily in the countryside, trying and executing accused heretics.

[Chance]

Very good. All approved other than "Another Heresy", as outlawing other religions is not present in Esshar so long as they don't break the established laws. There are certainly angel worshippers within the country, and priests of the church wouldn't go out of their way to discourage this.

Another Heresy
The Good Brothers of Kraus, the Divine Creator, Head of the Heavenly Host
Often just abbreviated to "The Good Brothers," this heretical sect first came to prominence in the 1300s, existing underground for the next century or so; it was most popular among the rural peasantry in the south of Esshar and, after a few decades, even a few noblemen fell victim to this spiritual plague. Even worse, certain clergymen had sympathies for them. 

The theology of the Good Brothers was Krausite, placing far more value on angels than on the stars, and was noted for its flagrant disregard for church hierarchy; the sect had no discernible ranks or leaders, instead arising out of discontent in the countryside. It was also deeply egalitarian, believing that all land and wealth ought to be shared.

Following a small rebellion, the sect was driven underground and after a few decades finally stamped out. To date, "crypto-Krausism" is a heavy charge to levy against a member of the clergy.