There are four categories of priesthood in Catholic Church . The head is the Pope, followed by cardinals, bishops, and then your every Sunday priest.
Become a Priest
In order to become a priest you first need a college education from a recognized theological school. Usually this means an aspiring priest would need a degree in Catholic philosophy or Canonical Law, and then get a masters in divinity.
Different schools will have different names for these things, but they serve mostly the same function.
In addition to education an aspiring priest must also be a man (born as a man), does not have a wife, and have no plans of getting one.
Once someone fulfills all the requirements a Bishop can ordain them as a priest and be put in charge of a church, or work with another priest in running a single church.
Become a Bishop
The next step is becoming a Bishop, and this is where things get political. This is because this is an extremely exclusive group.
At the latest count, there are 414,313 priests around the world. This may seem like a lot, until people remember that their ranks have been going down since 1975. This is causing a bit of a crisis in the Catholic Church, since the number of Catholics has been growing exponentially in the same period.
On the other hand, there are only 5,100 bishops as of 2009. Only one out of every eighty-one priests can become a Bishop, and the first step to becoming one is waiting for one of the existing Bishops in your area to be forced into retirement at 75 or die sooner than that.
This is where the politics play in, because no one applies to be Bishop, they’re chosen. Even before any space becomes available, the existing Bishops compile a secret list of priests that can become potential Bishops that they update every three years.
In order to be considered, you have to be a priest, be at least 35 years old, have at least five years of experience in being a priest, and have a doctorate in theology. But, even having all of that won’t guarantee that your name appears on the secret list.
Priests can engage in extra-curriculars to boost their chances, but the effect depends on the group of existing Bishops.
Once the Bishops have their list, they deliver it to the Apostolic Nuncio – the Pope’s ambassador to the country.
When a Bishop space becomes available, the Nuncio picks three names, conducts in-depth research on them, conducts interviews and sends his recommendations to a congress of Bishops in Vatican City.
If the congress doesn’t like any of the three, the Nuncio starts over with a fresh three names. But, if the congress is happy with one candidate, they send the recommendation to the Pope, who can either accept or veto the appointment. In case, of a veto, the Nuncio starts all over again.
Finding a replacement Bishop can take months, and on some occasions years. But, once you become a Bishop you are put in charge of a Cathedral, which oversees the operation of a number of local churches.
Bishops also get one of these snazzy spiral staff thingies
What is an Archbishop?
While not being an official rank in the Catholic heirarchy, the archbishop is more a title of honor than function. This title is given to Bishops overseeing more important cities and are (theoretically) in charge of more people.
But, don’t make the mistake of thinking that the arch prefix gives them more powers. Every Bishop enjoys the same powers and privileges as their arch counterparts – at least on paper.
If people give archbishops more respect because they think it’s a higher rank, then Bishops should probably do something about that.
Become a Cardinal
First things first, Cardinals are not higher than Bishops, they have the same rank. The only perk Cardinals get that Bishops do not is that they can select the new Pope.
As you can imagine, the selection of a Cardinal is even more political but far simpler process. The only way for a Bishop to become a Cardinal is if the Pope appoints you as one. This is a highly exclusive group with about 211 members.
Once you become a cardinal you get new stylish robes and vestments
Become a Pope
This is the part of the process that most people are familiar with. When a Pope resigns or dies, the eligible cardinals gather at a conclave, isolate themselves and elect a new Pope from their own ranks with a 2/3 majority vote – or 66.6% *mathematical gasp*.
Eligible cardinals are cardinals under 80 years old. As of August 2016, 111 out of the 211 cardinals are eligible.
Once you become Pope you become the Head of State of Vatican City and the leader of the Roman Catholic world.