I believe that the nation with the largest Christian population is China.
Brazil is not the largest; Brazil is the 5th largest nation in terms of population and area.
Russia is the largest nation in the world. It is in northern Europe and Asia
China
The largest population country is Indonesia.
Indonesia is generally cited as having the largest Muslim population of any nation.
The African country with the largest population is Nigeria. It's population is expected to reach 155,000,000 this year.
Israel.
Indonesia
area/ land size = Sudan population = Nigeria
The largest nation in Oceania, in both size and population, is Australia. (Only part of Indonesia is in Oceania.)
No. Alaska is the largest US state by area, and is not its own sovereign nation. California is the largest state by population, but it too is not its own sovereign nation. However it would be possible FOR California to be its own sovereign nation, because of its massive economy and population (california has the 8th largest economy in the world, about US$1.6 trillion, and the 34th largest population in the world)