It's comparing how Veganism and Atheism are very related to each other while Christianity and Meat Eating are just as similar to each other.

For example, to become an atheist or a vegan, you have to challenge your cultural views. You have to view the world with an open mind and research topics that may hurt your original cultural belief but will irregardlessly improve your intellect as you can now see the world from a new perspective.

To stay a Christian or meat eater, you have to keep a closed mind, you have to say every opposing evidence is wrong with no argument.

Here are some more similarities:

Most people are born religious and meat eater - Most people are not born vegan or atheist.
Religious and meat eaters have lower IQ - Vegans and atheists have higher IQ.
Religious and meat eaters don't question their belief - Vegans and atheists question all new information.
Religious and meat eaters only see the world in one way - Vegans and atheists have seen the world in different ways.

Also when you are an atheist debating against a Christian, it is like a Vegan debating against meat eaters. The christian or meat eater will not give strong arguments and will not listen to your arguments. The vegan or atheist will give strong arguments backed with factual information but more than likely it will fall on deaf ears.

Understand now?