A Christian state is a country that recognizes a form of Christianity as its official religion and often has a state church, which is a Christian denomination that supports the government and is supported by the government. Historically, the nations of Armenia,Aksum,Georgia, as well as the Roman Empire and Byzantine Empire declared themselves as Christian states. Today, several nations officially identify themselves as Christian states and/or have state churches, including Costa Rica,Denmark,England,Greece,Iceland,Liechtenstein,Monaco,Tonga,Tuvalu,Vatican City, and Zambia. A Christian state stands in contrast to a secular state, an atheist state, or another religious state, such as an Islamic state.
In 380 AD, the Edict of Thessalonica (Cunctos populos) made the Roman Empire a Christian state, establishing Nicene Christianity, in the form of its State Church, as its official religion.
After its fall, under the emperor Justinian (527-565), the "Byzantine Empire became the world's predominant Christian state, based on Roman law, Greek culture, and the Greek language." In this Christian state, in which faith in Jesus was upheld by nearly all of its subjects, an "enormous amount of artistic talent was poured into the construction of churches, church ceremonies, and church decoration". John Binns describes this era, writing that: