How many Christian countries are there in the world?

The World Christian Database has extensive data on 234 countries and 22 regions throughout the world.
http://www.worldchristiandatabase.org This list could just be countries that have people of the Christian faith.

This link is more detailed: https://en.wikipedia.org/wiki/State_religion#Christian_countries

Here's a link that list the countries by population. There are 193 countries on the list.
http://www.aneki.com/christian.html

Here's a site on the basic data for the religious makeup of 193 different countries. (Please note the reasons why data should be taken with a 'grain of salt.') Data is taken from the World Almanac and book of facts.

http://www.religioustolerance.org/rel_coun.htm

By my count, 18.

When I say "Christian country," I mean one whose government officially declares a certain religion as its "state religion."

Wiki lists countries that have state religions, and gives 20 that are officially Christian. I disagree with including Switzerland and the Russian Federation.

The tally is:
9 Roman Catholic nations in Europe and South America
4 Eastern Orthodox in Europe
4 Lutheran in Europe
1 Anglican....in England, of course!

https://en.wikipedia.org/wiki/State_religion#Christian_countries

"Switzerland has no official state religion, though most of the cantons (except Geneva and Neuchâtel) recognise official churches, in all cases including the Catholic Church and the Swiss Reformed Church."
https://en.wikipedia.org/wiki/Switzerland#Religion

"Christianity, Islam, Buddhism, and Judaism are Russia’s traditional religions, deemed part of Russia's "historical heritage" in a law passed in 1997."
https://en.wikipedia.org/wiki/Religion_in_Russia

Possibly other countries should be added to or excluded from the list.

I changed my mind on Switzerland. Since almost all the cantons endorse either the Catholic or Reformed Church, I'll go for saying the country as a whole is Christian.

At dinner today I asked a young Swiss if he considers it Christian, to which he shrugged and said for old people, yes. This is like Baloo's response to calling England a Christian country: Yes, like Tetley's the official beer.