1 in 3 people claim to be Christian
1 in 7 people are atheist/agnostic (Japan is the most atheistic country)
1 in 7 people are Hindu
1 in 5 people are Islamic
1 in 20 people are Buddhist

Approximately these 5 faiths make up 90% of world-views.

https://en.wikipedia.org/wiki/List_of_religious_populations