Yes, the word "Mass" should be capitalized when referring to the religious service in the Catholic Church.
No, church would not be capitalized in "at the back of the church."
Yes, the word "Church" is typically capitalized when referring to a specific church or the Christian church in general. However, it is not capitalized when used in a general sense (e.g., "the local church").
Yes, when referring to a specific religious institution or an organized body of believers, the word "Church" is typically capitalized. However, if referring to a general building or place of worship, it does not need to be capitalized.
Yes, "Vestry" should be capitalized when referring to the governing body of a church or chapel.
What Mass? If you are talking about a "Church" mass, then it would be located in a Church or Chapel.
in a church
Catholics have always assisted at Mass in a Church.
Yes, "Catholic" should be capitalized when referring to the Catholic Church or Catholicism as it is a proper noun.
Mass
It depends. If you are talking about the Eastern Orthodox Church, then yes, it is capitalized. But if you are using the adjective to describe something as being proper, then no, it is not capitalized. For example: The Orthodox Christians believe that their worship is the orthodox way of faith.
Mass in reference to a church service should always be capitalized because it is a proper noun. The Mass has the same construct wherever it is performed which makes it a unique entity similar perhaps to a play such as Les Miserables which would also be capitalized.When mass is used in the lower case it is meant as a reference to a quantity, often a large quantity.