How large a proportion of mankind believe in God?

Myt att kristendomen byggt Sverige Brännpunkt SvD: "Många tror att en majoritet av svenska folket är kristna. Det stämmer inte. Samtliga undersökningar visar att så inte är fallet. Sverige är ett av världens mest sekulära länder där mindre än 20 procent tror på någon eller några gudar. En överväldigande majoritet av de svenska med- borgarna är således ickereligiösa."

I want to investigate this further but from a preliminary survey it does seem to be a false statement to say that all investigations demonstrate that a majority of Swedes aren't Christian. It is important for Christer Stumark and the Humanists to claim that is possible to eradicate religion which I firmly believe is not possible due to the natural interest of the Divine among the majority of people.

First of all, Dagen published a Gallup study where it was asked if religion is important in your life and only around 20% claimed this in Scandinavia. However, this question is not the same as if one ask if people believe in God. In a genetically fairly similar country like the United States almost 50% go to Church once a week, the Pew Forum lists answers on the question if religion is important in your life and the national average is 56%.

Wikipedia gives information that 46%-85% of the Swedish population does not believe in God. Difficult to get a firm answer on this question in other words. However, as many as 65% baptise their child in Sweden and it is very difficult to believe that they would do this and not believe in God. Furthermore, as many as 84% bury their dead via the Church, also indicating that people become a little more religious at older age, or admit it more willingly, and that quite a few in actuality have a belief in God.

It is also interesting to speculate in the possibility that spirituality is a genetic trait and that the predilection for religiosity might vary on Earth. The Chinese, for example, managed to eradicate religion totally during their Maoistic era but it is coming back currently. The question is to what degree?