There is a formal way to address a bishop or archbishop, either by letter or in person. At times, you can be a little afraid, afraid of being rude. However, don't be apprehensive as the task is not that difficult. In time things will flow naturally. When in doubt, say “Your Excellency”, followed by his first and last name and “bishop of Ribeirão Preto” (or another city).
Steps
Method 1 of 2: Writing to a Bishop

Step 1. Call him "Your Most Reverend Excellency" followed by his full name
It is wise to refer to the bishop in a formal way. Catholic etiquette directs you to use “Your Most Reverend Excellency” followed by the bishop's first and last name.
For example, when writing a letter to Bishop Bernardo Pires, the letterhead should read “Your Excellency, Most Reverend Bernardo Pires”

Step 2. Regarding the title and name of the parish, follow the formal protocol
Include the word "bishop" and write his city on the outside of the envelope as well as in the letterhead. In the end, the text will look something like this:
Your Most Reverend Excellency Bernardo Pires, Bishop of Londrina

Step 3. Greet the bishop politely
When addressing a bishop, greet him appropriately: “Your Excellency” will do, but if you know him personally, it is okay to use “Dear…” (bishop's name and surname).
For example, both “Your Excellency, Bishop Bernardo Pires” and “Dear Bishop Bernardo Pires” are adequate forms, but it all depends on how well you two know each other

Step 4. End the letter with a graceful closing
Ending with the phrase “Sincerely, from your brother in Christ (your name)” will work in any case.

Step 5. Address an archbishop with absolutely formal terms
The archbishop's office is higher. Therefore, it is even more important that you follow the proper formalities. Roughly speaking, the guidelines are almost the same, with some variations:
- Use “Your Most Reverend Excellency” in the header, followed by the archbishop's name.
- Add “Archbishop” or “Apostolic Nuncio” to the address pronoun (“Your Excellency Most Reverend Bernardo Pires, Archbishop of Londrina” or “Your Excellency Most Reverend Bernardo Pires, Apostolic Nuncio of Brazil”).
- In the vocative, use the greeting “Most Excellent and Reverend Archbishop Bernardo Pires”.
- Closing with the phrase “Sincerely, from your brother in Christ (your name)” will also work in this case.
Method 2 of 2: Talking to a Bishop or Archbishop

Step 1. Greet him with the address pronoun "Your Excellency" followed by his first and last name
As with writing, you must honor an archbishop by addressing him personally. Therefore, use the phrase “Your Excellency” followed by his first and last name. Say, for example, “Your Excellency, Bishop Bernardo Pires? I was thinking of inviting him to the community dinner on Saturday.”

Step 2. Familiarize yourself with regional variations
The Catholic Church recommends using the standard greetings and treatment pronouns, which are always acceptable. However, in some regions there are some exceptions. In England, for example, citizens may address a bishop or archbishop as “Your Grace” instead of “Your Excellency”.
When in doubt, ask other people who attend your church about it

Step 3. Whenever talking to a bishop or archbishop, use the formal address pronouns
They are necessary, but that doesn't mean you can't have a normal, relaxed conversation with Catholic leaders. Just use the proper pronouns and treat them with respect. They will be happy to talk to you.