Are There Different Canons of the New Testament?

The Catholic Church, all the Eastern Orthodox churches and the Protestant churches have the same New Testament. Different denominations within Christendom have some additional books that we don't - which replicates what was happening in early Christianity up through the fourth century. If a book taught things that were deemed heretical, deemed false teaching, they weren't letting that one in. And so it ends up being kind of a circular process.