Advent or advent

Can somebody please help? Thanks.

If this is the title of a book or a pamphlet, then I would capitalize "advent".

If it is part of a normal sentence and not a title, then I would not capitalize "advent" (or "anniversary" or "founder").

It should not be capitalized. It is a common noun.

I believe if "advent" refers to the period on the Catholic calendar, it is capitalized, but that isn't the case here.

Correct, Advent, (with a capital) is the period in the run up to Christmas. Churches tend to light a candle on the four Sundays before Christmas.

If like me you can't stomach church there's chocolate filled Advent calendars.