The Meaningful Chocolate company estimates that there are more than one million advent calendars designed with animals on the front for pet lovers, with no reference to Christmas.
It believes the number of advent calendars based on the Christmas story is around 400,000.
David Marshall, the company's founder, told Premier: "Dog lovers are fine as a group of people who love their dogs. I'm a dog lover myself. But Christians really care about children.
"Supermarkets should offer a quality product that reflects some of the meaning of the season, and that will sell.
"There is one UK supermarket that I won't mention that is quite happy to offer pet owners an advent calendar that caters for them but will not offer Christians an advent calendar that connects with Christmas. That is a real shame."
Advent calendars have expanded in recent years, with calendars now based around football teams, boy bands and Disney films such as Frozen.
But Mr Marshall says they are ultimately worthless: "You would not let your child pick up rubbish from a shelf at any other time of the year, so why would you let them pick up a 75p advent calendar with Darth Vader looking out at you and say 'let's look at that for a month'.
"I think parents probably want to give a quality product; something that reflects values and a bit of educational fun."
And he believes selling Christian advent calendars makes business sense too.
"A lot of supermarkets are cutting back on their range. They might want to reflect that the Christian community is a big community and we are passionate about our faith."