To answer a few questions I got on the last one, the reason Islam is not separated is that there are many many Muslim nations, but I can count the Shia nations on one hand and it was too difficult to make the color scheme work. The same is true for why various folk religions are all lumped in together.
Interesting things about this map, perhaps most shocking to me is that Ethiopia is a primarily Orthodox Christian nation, I would’ve assumed really any other Abrahamic faith/denomination before the Orthodoxy. The baltic states are interesting with Lithuania being Catholic, Latvia being irreligious, and Estonia being protestant.
Whilst the UK, Australia, and Germany are primarily Christian, neither denomination has more of a share of the population than irreligiosity does. New Zealand and North Korea are majority irreligious, and Uruguay is majority-minority irreligious. Islam and Orthodox Christianity are the most compact religions, not really leaving their main sphere of influence.
Asia is the most religiously diverse region, with the only faith/denomination not present being Protestantism. Looking to Europe you can see the three types of Christianity being mostly separated along linguistic lines which is rather interesting. Judaism is the least represented religion, only being the majority in Israel.
(Source: reddit.com)